Abstract
Despite growing evidence linking sleep duration to chronic kidney disease (CKD), long-term trend analyses specific to the Korean population remain limited, and most previous studies have relied on broad intermediate sleep categories. This study analyzed trends in CKD prevalence by self-reported sleep duration among Korean adults. We included 87,246 Korean adults aged ≥19 years from the Korea National Health and Nutrition Examination Survey, 2007 to 2022. CKD was defined as an estimated glomerular filtration rate <60 mL/minutes/1.73 m2. Sleep duration was categorized into 5 groups (<6, 6–7, 7–8, 8–9, and ≥9 hours), with 7 to 8 hours as the reference. Weighted linear and logistic regression models provided β-coefficients and weighted odds ratios with 95% confidence intervals, sequentially adjusted for age, sex, body mass index, region, household income, education, smoking status, physician-diagnosed diabetes mellitus, hypertension, and dyslipidemia, and perceived stress. CKD prevalence declined across all 5 categories from 2007 to 2009 to 2020 to 2022 (<6 hours, 5.13% [95% confidence intervals, 4.12–6.13]–3.53% [2.74–4.33]; 7 to 8 hours, 2.37% [1.82–2.93]–1.52% [1.16–1.89]; ≥9 hours, 4.33% [3.17–5.48]–2.95% [2.18–3.72]). A U-shaped association was observed: relative to 7 to 8 hours, the fully adjusted odds of CKD were higher for <6 hours (weighted odds ratios 2.34 [2.04–2.69]) and ≥9 hours (2.07 [1.77–2.41]), with smaller elevations for 6 to 7 hours (1.18 [1.03–1.36]) and 8 to 9 hours (1.20 [1.05–1.37]). These estimates were essentially unchanged after adjustment for cardiometabolic comorbidity and perceived stress, and the pattern was present both among participants without and with each of these conditions. Short sleep was more strongly associated with CKD among females, whereas among adults aged ≥65 years the association was confined to long sleep. Trend slopes did not differ significantly before versus during the coronavirus disease 2019 pandemic in any category (all P > .05). In conclusion, CKD prevalence showed a U-shaped association with sleep duration that persisted after adjustment for cardiometabolic comorbidity and perceived stress. The absence of a significant change across the pandemic threshold should be interpreted in light of the short observation window relative to the natural history of CKD.
Keywords: chronic kidney disease, prevalence, Republic of Korea, sleep duration, trends
1. Introduction
Chronic kidney disease (CKD) affected an estimated 788 million adults worldwide in 2023, up from 378 million in 1990, with an age-standardized prevalence of 14.2%, and was the ninth leading cause of death globally, accounting for 1.48 million deaths.[1] Impaired kidney function additionally accounted for 11.5% of all cardiovascular deaths.[1] This rising burden is particularly notable given that mortality from many other chronic diseases has been declining. It is projected that by 2040, CKD will become the fifth leading cause of years of life lost globally, rising from sixteenth in 2016.[2] Furthermore, to address the growing prevalence of CKD and the resulting increase in healthcare costs in South Korea, the Korean Society of Nephrology has introduced a new policy initiative, the Kidney Health Plan 2033.[3] The disease is closely associated with a wide range of biological, environmental, and lifestyle risk factors.[4]
Recent studies have highlighted the relationship between sleep duration and CKD.[5] Insufficient or excessive sleep may affect kidney function through sympathetic activation, systemic inflammation, and metabolic dysregulation. Sleep duration may also serve as a marker of underlying psychological state, since both short and long sleep are common features of depression, anxiety, and chronic stress, conditions that themselves influence renal and cardiometabolic health through hypothalamic-pituitary-adrenal (HPA) axis activation.[6,7] The COVID-19 pandemic, a period of widespread behavioral change and psychological distress, provides a setting in which this question is particularly relevant.[8]
Although previous studies have examined the association between sleep duration and CKD, long-term trend analyses specific to the Korean population remain limited, and most have relied on broad intermediate sleep categories that may obscure variation within the most populated range. We hypothesized that CKD prevalence would show a U-shaped association with sleep duration, with the lowest prevalence at 7 to 8 hours, and that this association would be independent of established cardiometabolic comorbidity and of perceived stress, and would persist across the pandemic threshold; the latter not because a two-year window would be expected to alter the prevalence of a slowly progressive disease, but because the pandemic offers a natural setting in which to test the stability of this association under abrupt behavioral change. Accordingly, this study aimed to describe long-term trends in CKD prevalence by sleep duration among Korean adults and to identify subgroups in which the association is most pronounced.
2. Methods
2.1. Data source and study population
This study used data from the Korea National Health and Nutrition Examination Survey (KNHANES, 2007–2022), an ongoing nationally representative cross-sectional survey conducted annually by the Korea Disease Control and Prevention Agency (KDCA).[9] The KNHANES employs a multistage stratified probability sampling design with a sampling frame derived from the most recent population and housing census, and comprises a health interview, a health examination, and a nutrition survey. It provides sociodemographic and lifestyle information, physician-diagnosed disease status, anthropometric measurements, and standardized laboratory measurements, including serum creatinine.
Although older adults constitute the principal risk group for CKD,[10] we included all adults aged ≥19 years in order to characterize the full adult age spectrum and to enable age-stratified comparisons between working-age and older adults. Participants were eligible if they had available data on serum creatinine, sleep duration, and all covariates of interest. Of 126,446 survey respondents between 2007 and 2022, 39,200 were excluded because they were younger than 19 years (n = 27,005) or had missing information on clinical covariates, smoking status, sleep duration, household income, an estimated glomerular filtration rate (eGFR), or body mass index (BMI) (n = 12,195), yielding a final analytic sample of 87,246 adults (Figure S1, Supplemental Digital Content 1). Participants were grouped into 5 survey periods in accordance with the KNHANES sampling design (2007–2009, n = 16,202; 2010–2012, n = 16,760; 2013–2015, n = 14,347; 2016–2019, n = 23,803; and 2020–2022, n = 16,134), with 2020 to 2022 designated as the COVID-19 pandemic period and the preceding cycles as the pre-pandemic period. The research protocol was approved by the Institutional Review Boards of the KDCA (approval numbers 2007-02CON-04-P, 2008-04EXP-01-C, 2009-01CON-03-2C, 2010-02CON-21-C, 2011-02CON-06-C, 2012-01EXP-01-2C, 2013-07CON-03-4C, 2013-12EXP-03-5C, 2018-01-03-P-A, 2018-01-03-C-A, 2018-01-03-2C-A, 2018-01-03-5C-A, and 2018-01-03-4C-A). All participants provided written informed consent before participation. KNHANES data are publicly available and are widely used as a resource for epidemiological research. This study was conducted in accordance with the principles of the Declaration of Helsinki.
2.2. Covariates
To identify factors associated with CKD and sleep duration, eleven covariates related to participant characteristics were examined: age groups (19–64 years and ≥65 years), sex, region of residence (urban and rural),[11,12] BMI categories following the Asia-Pacific guidelines (underweight [<18.5 kg/m2], normal [18.5–22.9 kg/m2], overweight [23.0–24.9 kg/m2], and obesity [≥25.0 kg/m2]),[13] educational background (high school level or lower and college level or higher), household income (categorized into lowest and second quartiles and third and highest quartiles), smoking status (current smoker, ex-smoker, and nonsmoker), diabetes mellitus, hypertension, dyslipidemia, and perceived stress. The latter 4 covariates were incorporated because diabetes mellitus, hypertension, and dyslipidemia are the principal established determinants of CKD, and because psychosocial stress may confound the association between sleep duration and renal function through HPA axis activation and systemic inflammation.[6,14] Diabetes mellitus, hypertension, and dyslipidemia were defined using the corresponding physician-diagnosis variables in the KNHANES health interview (self-reported lifetime diagnosis by a physician; yes vs no). Perceived stress was dichotomized from a single 4-point item into high (“a great deal” or “quite a lot”) and low (“a little” or “hardly any”), with nonresponse coded as unknown.
Household income was stratified into 4 quartiles according to standardized income data from the KNHANES sample households and the overall population. Age was dichotomized at 65 years, as CKD prevalence and its associated risk factors, including comorbidity burden, diminished renal reserve, and altered sleep architecture, differ substantially between working-age and older adults.[15] These covariates were assessed to evaluate their potential contributions to CKD according to sleep duration.
2.3. Definition of CKD status and sleep duration categorization
The primary outcome, CKD status, was defined in accordance with the Kidney Disease Improving Global Outcomes (KDIGO) guidelines as eGFR below 60 mL/minutes/1.73 m2,[16] corresponding to KDIGO glomerular filtration rate categories G3a–G5. eGFR was calculated using the 4-variable Modification of Diet in Renal Disease study equation:
Although the CKD Epidemiology Collaboration equation is currently preferred for clinical glomerular filtration rate estimation, the Modification of Diet in Renal Disease equation was applied uniformly to all survey cycles to preserve comparability of eGFR estimates across the 16-year study period. Serum creatinine was measured by colorimetric assay under the standardized KNHANES laboratory quality-control program.[17] The contracted clinical laboratory and analytical platform changed several times over the study period, and reagent systems in 2007 to 2009 differed from those used subsequently. Serum creatinine was not among the analytes for which the KDCA issued conversion equations or advised against year-to-year comparison. CKD was operationalized on the basis of reduced eGFR alone; individuals with preserved eGFR and isolated albuminuria were therefore not classified as having CKD.
Sleep duration was ascertained by self-report, and the survey instrument changed over the study period. From 2007 to 2015, participants reported a single average daily sleep duration in whole hours. From 2016 onward, weekday and weekend sleep durations were assessed separately, reported directly in 2016 to 2020 and 2022, and derived from reported bedtimes and wake times in 2021, and a weighted daily average was calculated as to reflect the number of weekdays and weekend days per week. Participants with missing sleep duration data, including those who responded “don’t know” or did not respond, were excluded from the analysis (Figure S1, Supplemental Digital Content 1). Sleep duration was then categorized into 5 groups using left-closed intervals (<6, ≥6 to <7, ≥7 to <8, ≥8 to <9, and ≥9 hours), with 7 to 8 hours designated as the reference category, in accordance with the National Sleep Foundation and American Academy of Sleep Medicine recommendations that adults obtain 7 to 9 hours of sleep per night and because the 7 to 8 hour range represented the modal interval in the present sample.[18,19] Compared with the broader intermediate categories used in previous studies of sleep duration and renal function, this finer categorization allows non-linear associations within the intermediate range to be detected rather than obscured.
2.4. Statistical analysis
All analyses accounted for the complex, multistage stratified sampling design of the KNHANES using the SAS SURVEY procedures, incorporating the sampling weights, stratification variables, and primary sampling units provided by the KDCA.[17] Integrated weights were recalculated for the pooled 2007 to 2022 dataset in accordance with the KDCA analytic guidelines, thereby accounting for annual variation in participant numbers and yielding estimates representative of the noninstitutionalized Korean adult population. Weighted linear regression models were used to estimate linear trends in CKD prevalence over time.[9] In these models, the dependent variable was CKD prevalence and the independent variable was survey period, fitted separately within each sleep duration category and within each demographic and socioeconomic subgroup. β-coefficients are presented multiplied by 10 for ease of presentation, given their small magnitude, with 95% confidence intervals (CIs). To formally test whether the COVID-19 pandemic altered the preexisting temporal trend, we fitted separate weighted linear regression models for the pre-pandemic (2007–2019) and pandemic (2020–2022) periods within each sleep duration category and subgroup, and calculated the difference between the 2 period-specific slopes (βdiff). Its standard error was obtained by error propagation from the 2 period-specific standard errors, and the corresponding 95% CIs and P values are reported. Trends were therefore compared statistically within each stratum rather than assessed qualitatively or only in the overall cohort.
Multivariable logistic regression models were used to estimate weighted odds ratios (wORs) for CKD.[13] The dependent variable was CKD status, and the primary independent variable was sleep duration category, with 7 to 8 hours as the reference. Three sequentially adjusted models were fitted: Model 1 adjusted for sociodemographic and lifestyle variables (age, sex, BMI, region of residence, household income, educational attainment, and smoking status); Model 2 additionally adjusted for physician-diagnosed diabetes mellitus, hypertension, and dyslipidemia; and Model 3 further adjusted for perceived stress. This sequential approach was adopted to assess the extent to which the association between sleep duration and CKD was attenuated by major cardiometabolic comorbidities and by perceived stress. Stratified analyses were conducted by age group, sex, BMI category, region of residence, household income, educational attainment, and smoking status. All analyses were performed using SAS software (version 9.4; SAS Institute, Cary). Two-sided P values <.05 were considered statistically significant.
3. Results
3.1. Participants
A total of 87,246 participants were included in the analysis. Of 126,446 KNHANES respondents surveyed between 2007 and 2022, 27,005 were excluded because they were younger than 19 years and a further 12,195 because of missing data on clinical covariates, smoking status, sleep duration, household income, eGFR, or BMI (Figure S1, Supplemental Digital Content 1). The weighted baseline characteristics are presented in Table 1: sex (male, 50.00% [95% CI, 49.61 to 50.40]), age (19–64 years, 83.84% [95% CI, 83.32 to 84.36]; ≥65 years, 16.16% [95% CI, 15.64 to 16.68]), and CKD (2.16% [95% CI, 2.03 to 2.29]).
Table 1.
General characteristics of Korean adults aged ≥19 years, KNHANES 2007 to 2022 (n = 87,246).
| Characteristic | Total | Before the pandemic | During the pandemic | |||
|---|---|---|---|---|---|---|
| 2007–2009 | 2010–2012 | 2013–2015 | 2016–2019 | 2020–2022 | ||
| Overall, n | 87,246 | 16,202 | 16,760 | 14,347 | 23,803 | 16,134 |
| Crude rate, n (%) | ||||||
| Sex, n (%) | ||||||
| Male | 37,965 (43.51) | 6927 (42.75) | 7167 (42.76) | 6190 (43.14) | 10,541 (44.28) | 7140 (44.25) |
| Female | 49,281 (56.49) | 9275 (57.25) | 9593 (57.24) | 8157 (56.86) | 13,262 (55.72) | 8994 (55.75) |
| Age, n (%) | ||||||
| 19–64 yr | 66,064 (75.72) | 12,767 (78.80) | 12,988 (77.49) | 11,073 (77.18) | 17,806 (74.81) | 11,430 (70.84) |
| ≥65 yr | 21,182 (24.28) | 3435 (21.20) | 3772 (22.51) | 3274 (22.82) | 5997 (25.19) | 4704 (29.16) |
| BMI, n (%)* | ||||||
| Underweight | 3599 (4.13) | 731 (4.51) | 732 (4.37) | 583 (4.06) | 890 (3.74) | 663 (4.11) |
| Normal weight | 33,789 (38.73) | 6404 (39.53) | 6753 (40.29) | 5638 (39.30) | 9162 (38.49) | 5832 (36.15) |
| Overweight | 20,411 (23.39) | 3900 (24.07) | 3929 (23.44) | 3411 (23.78) | 5475 (23.00) | 3696 (22.91) |
| Obesity | 29,447 (33.75) | 5167 (31.89) | 5346 (31.90) | 4715 (32.86) | 8276 (34.77) | 5943 (36.84) |
| Region, n (%) | ||||||
| Urban | 39,579 (45.36) | 6995 (43.17) | 7702 (45.95) | 6603 (46.02) | 11,111 (46.68) | 7168 (44.43) |
| Rural | 47,667 (54.64) | 9207 (56.83) | 9058 (54.05) | 7744 (53.98) | 12,692 (53.32) | 8966 (55.57) |
| Household income, n (%)† | ||||||
| Lowest and second quartile | 43,203 (49.52) | 8051 (49.69) | 8242 (49.18) | 7042 (49.08) | 11,868 (49.86) | 8000 (49.58) |
| Third and highest quartile | 44,043 (50.48) | 8151 (50.31) | 8518 (50.82) | 7305 (50.92) | 11,935 (50.14) | 8134 (50.42) |
| Education, n (%) | ||||||
| High school or lower | 50,051 (57.37) | 10,841 (66.91) | 10,459 (62.40) | 8412 (58.63) | 12,404 (52.11) | 7935 (49.18) |
| College or higher | 34,939 (40.05) | 5329 (32.89) | 6282 (37.48) | 5774 (40.25) | 10,277 (43.18) | 7277 (45.10) |
| Unknown | 2256 (2.59) | 32 (0.20) | 19 (0.11) | 161 (1.12) | 1122 (4.71) | 922 (5.71) |
| Smoking status, n (%) | ||||||
| Smoker | 16,678 (19.12) | 3607 (22.26) | 3460 (20.64) | 2731 (19.04) | 4313 (18.12) | 2567 (15.91) |
| Ex-smoker | 18,331 (21.01) | 3124 (19.28) | 3406 (20.32) | 2840 (19.80) | 5168 (21.71) | 3793 (23.51) |
| Nonsmoker | 52,237 (59.87) | 9471 (58.46) | 9894 (59.03) | 8776 (61.17) | 14,322 (60.17) | 9774 (60.58) |
| Diabetes mellitus, n (%)‡ | ||||||
| Non-DM group | 79,377 (90.98) | 15,098 (93.19) | 15,365 (91.68) | 13,119 (91.44) | 21,521 (90.41) | 14,274 (88.47) |
| DM group | 7869 (9.02) | 1104 (6.81) | 1395 (8.32) | 1228 (8.56) | 2282 (9.59) | 1860 (11.53) |
| Hypertension, n (%)‡ | ||||||
| Non-hypertension group | 67,045 (76.85) | 13,064 (80.63) | 13,034 (77.77) | 11,184 (77.95) | 17,981 (75.54) | 11,782 (73.03) |
| Hypertension group | 20,201 (23.15) | 3138 (19.37) | 3726 (22.23) | 3163 (22.05) | 5822 (24.46) | 4352 (26.97) |
| Dyslipidemia, n (%)‡ | ||||||
| Non-dyslipidemia group | 74,004 (84.82) | 15,045 (92.86) | 14,968 (89.31) | 12,259 (85.45) | 19,400 (81.50) | 12,332 (76.43) |
| Dyslipidemia group | 13,242 (15.18) | 1157 (7.14) | 1792 (10.69) | 2088 (14.55) | 4403 (18.50) | 3802 (23.57) |
| Perceived stress, n (%)§ | ||||||
| High stress | 22,900 (26.25) | 4617 (28.50) | 4404 (26.28) | 3466 (24.16) | 6287 (26.41) | 4126 (25.57) |
| Low stress | 63,733 (73.05) | 11,562 (71.36) | 12,321 (73.51) | 10,704 (74.61) | 17,260 (72.51) | 11,886 (73.67) |
| Unknown | 613 (0.70) | 23 (0.14) | 35 (0.21) | 177 (1.23) | 256 (1.08) | 122 (0.76) |
| Sleep time, n (%)‖ | ||||||
| <6 h | 13,138 (15.06) | 2454 (15.15) | 2562 (15.29) | 2313 (16.12) | 3404 (14.30) | 2405 (14.91) |
| 6–7 h | 20,364 (23.34) | 4071 (25.13) | 4374 (26.10) | 3967 (27.65) | 4803 (20.18) | 3149 (19.52) |
| 7–8 h | 25,611 (29.35) | 4573 (28.22) | 4769 (28.45) | 3976 (27.71) | 7416 (31.16) | 4877 (30.23) |
| 8–9 h | 19,456 (22.30) | 3643 (22.48) | 3753 (22.39) | 2936 (20.46) | 5414 (22.75) | 3710 (22.99) |
| ≥9 h | 8677 (9.95) | 1461 (9.02) | 1302 (7.77) | 1155 (8.05) | 2766 (11.62) | 1993 (12.35) |
| CKD, n (%)¶ | ||||||
| Non-CKD group | 84,540 (96.90) | 603 (3.72) | 451 (2.69) | 447 (3.12) | 739 (3.10) | 466 (2.89) |
| CKD group | 2706 (3.10) | 15,599 (96.28) | 16,309 (97.31) | 13,900 (96.88) | 23,064 (96.90) | 15,668 (97.11) |
| Weighted rate (95% CI) | ||||||
| Sex (95% CI) | ||||||
| Male | 50.00 (49.61–50.40) | 50.00 (49.22–50.78) | 49.82 (49.03–50.61) | 49.80 (49.01–50.59) | 50.20 (49.56–50.84) | 50.02 (49.28–50.75) |
| Female | 50.00 (49.60–50.39) | 50.00 (49.22–50.78) | 50.18 (49.39–50.97) | 50.20 (49.41–50.99) | 49.80 (49.16–50.44) | 49.98 (49.25–50.72) |
| Age (95% CI) | ||||||
| 19–64 yr | 83.84 (83.32–84.36) | 87.63 (86.82–88.45) | 87.06 (86.30–87.82) | 86.29 (85.49–87.09) | 83.71 (82.88–84.54) | 81.44 (80.38–82.49) |
| ≥65 yr | 16.16 (15.64–16.68) | 12.37 (11.55–13.18) | 12.94 (12.18–13.70) | 13.71 (12.91–14.51) | 16.29 (15.46–17.12) | 18.56 (17.51–19.62) |
| BMI (95% CI)* | ||||||
| Underweight | 4.39 (4.17–4.60) | 4.73 (4.24–5.22) | 4.69 (4.27–5.11) | 4.59 (4.15–5.02) | 4.00 (3.69–4.32) | 4.32 (3.91–4.73) |
| Normal weight | 37.58 (37.09–38.07) | 39.51 (38.54–40.47) | 40.11 (39.13–41.09) | 39.79 (38.83–40.75) | 38.51 (37.75–39.27) | 35.50 (34.58–36.43) |
| Overweight | 22.80 (22.40–23.20) | 23.76 (22.94–24.57) | 22.88 (22.11–23.65) | 23.18 (22.37–23.98) | 22.58 (21.95–23.21) | 22.52 (21.78–23.27) |
| Obesity | 35.23 (34.72–35.75) | 32.01 (31.02–32.99) | 32.32 (31.33–33.30) | 32.45 (31.52–33.37) | 34.91 (34.11–35.70) | 37.65 (36.67–38.64) |
| Region (95% CI) | ||||||
| Urban | 46.14 (44.79–47.48) | 46.84 (44.22–49.47) | 46.85 (44.59–49.11) | 47.02 (44.94–49.10) | 46.85 (44.35–49.35) | 45.27 (42.32–48.23) |
| Rural | 53.86 (52.52–55.21) | 53.16 (50.53–55.78) | 53.15 (50.89–55.41) | 52.98 (50.90–55.06) | 53.15 (50.65–55.65) | 54.73 (51.77–57.68) |
| Household income (95% CI)† | ||||||
| Lowest and second quartile | 49.63 (48.70–50.56) | 48.97 (46.98–50.96) | 52.13 (50.57–53.69) | 49.64 (47.87–51.41) | 50.28 (48.82–51.75) | 48.85 (47.07–50.62) |
| Third and highest quartile | 50.37 (49.44–51.30) | 51.03 (49.04–53.02) | 47.87 (46.31–49.43) | 50.36 (48.59–52.13) | 49.72 (48.25–51.18) | 51.15 (49.38–52.93) |
| Education (95% CI) | ||||||
| High school or lower | 47.93 (47.09–48.77) | 59.73 (58.12–61.34) | 56.85 (55.33–58.38) | 51.46 (49.94–52.97) | 45.37 (43.96–46.77) | 42.46 (40.92–43.99) |
| College or higher | 48.81 (47.94–49.68) | 40.10 (38.48–41.71) | 43.06 (41.54–44.58) | 47.38 (45.85–48.92) | 49.74 (48.29–51.18) | 52.77 (51.12–54.42) |
| Unknown | 3.26 (2.99–3.52) | 0.17 (0.10–0.25) | 0.09 (0.04–0.14) | 1.16 (0.88–1.43) | 4.90 (4.42–5.37) | 4.77 (4.23–5.31) |
| Smoking status (95% CI) | ||||||
| Smoker | 21.48 (21.00–21.95) | 26.89 (25.93–27.85) | 26.68 (25.73–27.62) | 23.07 (22.12–24.02) | 21.28 (20.52–22.04) | 18.27 (17.41–19.13) |
| Ex-smoker | 22.45 (22.05–22.85) | 20.04 (19.26–20.81) | 19.85 (19.11–20.59) | 19.73 (18.95–20.51) | 21.85 (21.25–22.45) | 24.64 (23.89–25.39) |
| nonsmoker | 56.08 (55.59–56.56) | 53.08 (52.12–54.03) | 53.47 (52.57–54.37) | 57.20 (56.24–58.16) | 56.87 (56.11–57.63) | 57.09 (56.17–58.01) |
| Diabetes mellitus (95% CI)‡ | ||||||
| Non-DM group | 92.13 (91.85–92.41) | 94.62 (94.17–95.06) | 93.74 (93.31–94.17) | 93.44 (92.97–93.91) | 92.42 (92.00–92.85) | 90.60 (90.05–91.16) |
| DM group | 7.87 (7.59–8.15) | 5.38 (4.94–5.83) | 6.26 (5.83–6.69) | 6.56 (6.09–7.03) | 7.58 (7.15–8.00) | 9.40 (8.84–9.95) |
| Hypertension (95% CI)‡ | ||||||
| Non-hypertension group | 80.75 (80.27–81.23) | 84.84 (84.07–85.62) | 83.54 (82.74–84.34) | 83.42 (82.63–84.22) | 80.48 (79.71–81.24) | 78.40 (77.44–79.35) |
| Hypertension group | 19.25 (18.77–19.73) | 15.16 (14.38–15.93) | 16.46 (15.66–17.26) | 16.58 (15.78–17.37) | 19.52 (18.76–20.29) | 21.60 (20.65–22.56) |
| Dyslipidemia (95% CI)‡ | ||||||
| Non-dyslipidemia group | 85.11 (84.71–85.52) | 93.82 (93.33–94.31) | 91.92 (91.42–92.42) | 88.66 (88.10–89.22) | 84.39 (83.80–84.98) | 80.35 (79.56–81.15) |
| Dyslipidemia group | 14.89 (14.48–15.29) | 6.18 (5.69–6.67) | 8.08 (7.58–8.58) | 11.34 (10.78–11.90) | 15.61 (15.02–16.20) | 19.65 (18.85–20.44) |
| Perceived stress (95% CI)§ | ||||||
| High stress | 27.32 (26.81–27.84) | 29.03 (28.10–29.97) | 27.56 (26.67–28.44) | 25.91 (24.99–26.84) | 28.01 (27.27–28.74) | 26.79 (25.80–27.78) |
| Low stress | 72.03 (71.52–72.54) | 70.83 (69.89–71.77) | 72.25 (71.37–73.14) | 72.98 (72.05–73.91) | 70.94 (70.19–71.68) | 72.55 (71.57–73.54) |
| Unknown | 0.65 (0.56–0.73) | 0.14 (0.06–0.21) | 0.19 (0.11–0.27) | 1.11 (0.89–1.33) | 1.06 (0.89–1.22) | 0.66 (0.50–0.81) |
| Sleep time (95% CI)‖ | ||||||
| <6 h | 13.33 (12.99–13.68) | 13.40 (12.72–14.08) | 13.37 (12.70–14.05) | 14.75 (14.03–15.46) | 13.61 (12.99–14.24) | 12.90 (12.26–13.55) |
| 6–7 h | 22.27 (21.84–22.70) | 25.89 (24.86–26.93) | 26.80 (25.87–27.73) | 27.93 (27.05–28.80) | 20.14 (19.52–20.77) | 19.70 (18.91–20.49) |
| 7–8 h | 30.50 (30.05–30.96) | 28.32 (27.34–29.30) | 28.72 (27.82–29.61) | 28.72 (27.85–29.58) | 31.91 (31.18–32.64) | 31.41 (30.56–32.26) |
| 8–9 h | 23.22 (22.79–23.65) | 22.98 (22.01–23.95) | 23.15 (22.30–24.00) | 20.82 (20.00–21.64) | 22.92 (22.28–23.56) | 23.93 (23.13–24.73) |
| ≥9 h | 10.67 (10.27–11.08) | 9.41 (8.00–10.82) | 7.96 (7.36–8.55) | 7.79 (7.26–8.33) | 11.42 (10.88–11.96) | 12.06 (11.33–12.79) |
| CKD (95% CI)¶ | ||||||
| Non-CKD group | 97.84 (97.71–97.97) | 97.02 (96.67–97.37) | 98.23 (98.01–98.44) | 97.84 (97.59–98.09) | 97.78 (97.57–97.98) | 97.99 (97.74–98.23) |
| CKD group | 2.16 (2.03–2.29) | 2.98 (2.63–3.33) | 1.77 (1.56–1.99) | 2.16 (1.91–2.41) | 2.22 (2.02–2.43) | 2.01 (1.77–2.26) |
BMI = body mass index, CI = confidence interval, CKD = chronic kidney disease, DM = diabetes mellitus, KNHANES = Korea National Health and Nutrition Examination Survey.
BMI was categorized according to the Asia-Pacific guidelines: underweight (<18.5 kg/m2), normal weight (18.5–22.9 kg/m2), overweight (23.0–24.9 kg/m2), and obesity (≥25.0 kg/m2).
Household income was calculated in quartiles based on standardized income data from the KNHANES sample households and then dichotomized into the lower half (lowest and second quartiles) and the upper half (third and highest quartiles).
Diabetes mellitus, hypertension, and dyslipidemia were defined using the corresponding physician-diagnosis variables in the KNHANES health interview (self-reported lifetime diagnosis by a physician; yes vs no).
Perceived stress was dichotomized from a single 4-point item into high (“a great deal” or “quite a lot”) and low (“a little” or “hardly any”), with nonresponse coded as unknown.
Sleep duration was self-reported and categorized using left-closed intervals (<6, ≥6 to <7, ≥7 to <8, ≥8 to <9, and ≥9 hours).
CKD was defined as an estimated glomerular filtration rate <60 mL/minutes/1.73 m2, calculated using the 4-variable Modification of Diet in Renal Disease study equation.
3.2. Temporal trends in CKD prevalence by sleep duration
Table 2 and Figure 1 present CKD prevalence by sleep duration category before and during the COVID-19 pandemic. CKD prevalence declined across all 5 sleep duration categories over the study period. Prevalence in the <6 hour group fell from 5.13% [95% CI, 4.12–6.13] in 2007 to 2009 to 3.53% [95% CI, 2.74–4.33] in 2020–2022, and in the ≥9 hour group from 4.33% [95% CI, 3.17–5.48] to 2.95% [95% CI, 2.18–3.72]. The 7 to 8 hour reference group declined from 2.37% [95% CI, 1.82–2.93] to 1.52% [95% CI, 1.16–1.89] and consistently showed the lowest prevalence of any category throughout the study period, while the adjacent 6 to 7 hour (2.38%–1.84%) and 8 to 9 hour (2.60%–1.51%) groups occupied intermediate positions. This ordering describes a U-shaped distribution that was stable across all 5 survey periods.
Table 2.
Weighted prevalence and β-coefficients for trends in CKD by sleep duration category before and during the COVID-19 pandemic, KNHANES 2007 to 2022.
| Variables | Before the pandemic | During the pandemic | Trends in the before pandemic, β (95% CI)‖ | Trends in the pandemic, β (95% CI)‖ | βdiff between 2007–2019 and 2020–2022 (95% CI)¶ | P-value | |||
|---|---|---|---|---|---|---|---|---|---|
| 2007–2009 | 2010–2012 | 2013–2015 | 2016–2019 | 2020–2022 | |||||
| Overall | |||||||||
| <6 h | 5.13 (4.12–6.13) | 3.63 (2.84–4.42) | 3.06 (2.32–3.81) | 3.55 (2.81–4.29) | 3.53 (2.74–4.33) | −0.044 (−0.077–−0.011) | 0.053 (−0.237–0.343) | 0.097 (−0.194–0.389) | .513 |
| 6–7 h | 2.38 (1.80–2.95) | 1.42 (1.09–1.75) | 1.76 (1.30–2.21) | 2.13 (1.71–2.55) | 1.84 (1.40–2.28) | −0.010 (−0.047–0.027) | −0.033 (−0.302–0.237) | −0.022 (−0.294–0.249) | .871 |
| 7–8 h | 2.37 (1.82–2.93) | 1.27 (0.96–1.59) | 1.68 (1.31–2.05) | 1.49 (1.22–1.77) | 1.52 (1.16–1.89) | −0.044 (−0.079–−0.009) | 0.042 (−0.239–0.323) | 0.086 (−0.197–0.369) | .551 |
| 8–9 h | 2.60 (1.94–3.26) | 1.63 (1.21–2.05) | 2.14 (1.65–2.64) | 1.96 (1.61–2.32) | 1.51 (1.09–1.93) | −0.024 (−0.059–0.011) | −0.016 (−0.391–0.359) | 0.008 (−0.369–0.384) | .968 |
| ≥9 h | 4.33 (3.17–5.48) | 2.05 (1.25–2.85) | 3.72 (2.71–4.74) | 3.36 (2.66–4.06) | 2.95 (2.18–3.72) | −0.016 (−0.055–0.024) | −0.076 (−0.407 to 0.254) | −0.061 (−0.393–0.272) | .720 |
| Sex | |||||||||
| Male | |||||||||
| <6 h | 3.62 (2.39–4.85) | 3.59 (2.33–4.86) | 2.17 (1.27–3.06) | 2.91 (1.92–3.89) | 3.06 (1.99–4.13) | −0.027 (−0.081–0.026) | −0.199 (−0.677–0.278) | −0.172 (−0.652–0.309) | .483 |
| 6–7 h | 1.44 (0.93–1.95) | 0.94 (0.57–1.31) | 1.72 (1.11–2.33) | 2.19 (1.61–2.77) | 1.93 (1.31–2.54) | 0.063 (0.014–0.112) | 0.013 (−0.351–0.378) | −0.050 (−0.417–0.318) | .791 |
| 7–8 h | 1.49 (0.91–2.06) | 1.48 (0.99–1.96) | 2.41 (1.78–3.04) | 1.50 (1.10–1.89) | 1.66 (1.08–2.24) | 0.001 (−0.041–0.044) | 0.055 (−0.350–0.460) | 0.054 (−0.354–0.461) | .796 |
| 8–9 h | 2.45 (1.51–3.38) | 2.27 (1.53–3.02) | 2.81 (1.96–3.66) | 2.41 (1.85–2.98) | 1.58 (1.03–2.14) | 0.003 (−0.042–0.048) | −0.213 (−0.679–0.253) | −0.216 (−0.684–0.252) | .366 |
| ≥9 h | 4.68 (2.74–6.62) | 2.79 (1.35–4.24) | 3.40 (2.06–4.74) | 2.89 (1.95–3.83) | 3.02 (1.93–4.11) | −0.045 (−0.105–0.014) | −0.045 (−0.476–0.387) | 0.001 (−0.434–0.436) | .997 |
| Female | |||||||||
| <6 h | 6.33 (4.81–7.84) | 3.65 (2.67–4.64) | 3.75 (2.64–4.86) | 4.16 (3.13–5.18) | 3.94 (2.86–5.02) | −0.052 (−0.093–−0.010) | 0.196 (−0.163–0.556) | 0.248 (−0.114–0.610) | .180 |
| 6–7 h | 3.47 (2.43–4.52) | 2.01 (1.44–2.58) | 1.80 (1.18–2.42) | 2.07 (1.45–2.68) | 1.74 (1.09–2.40) | −0.070 (−0.123–−0.018) | −0.091 (−0.506–0.323) | −0.021 (−0.439–0.396) | .921 |
| 7–8 h | 3.33 (2.36–4.30) | 1.06 (0.68–1.44) | 0.92 (0.57–1.27) | 1.49 (1.12–1.85) | 1.38 (0.94–1.82) | −0.093 (−0.148–−0.038) | 0.029 (−0.368–0.426) | 0.122 (−0.279–0.522) | .552 |
| 8–9 h | 2.75 (1.75–3.75) | 1.02 (0.61–1.44) | 1.48 (0.91–2.05) | 1.53 (1.10–1.95) | 1.44 (0.89–1.99) | −0.061 (−0.120–−0.003) | 0.199 (−0.320–0.719) | 0.261 (−0.262–0.783) | .328 |
| ≥9 h | 4.04 (2.66–5.42) | 1.47 (0.63–2.31) | 3.97 (2.51–5.43) | 3.76 (2.77–4.74) | 2.89 (1.91–3.88) | 0.009 (−0.042–0.060) | −0.114 (−0.609–0.381) | −0.123 (−0.620–0.374) | .627 |
| Age | |||||||||
| 19–64 yr | |||||||||
| <6 h | 1.95 (1.12–2.79) | 0.76 (0.21–1.31) | 0.92 (0.42–1.43) | 1.17 (0.66–1.68) | 0.75 (0.31–1.18) | −0.052 (−0.131–0.026) | 0.172 (−0.560–0.904) | 0.224 (−0.512–0.960) | .550 |
| 6–7 h | 1.01 (0.62–1.41) | 0.53 (0.29–0.78) | 0.96 (0.57–1.36) | 0.81 (0.49–1.13) | 0.63 (0.27–0.99) | −0.010 (−0.074–0.054) | −0.108 (−0.651–0.434) | −0.099 (−0.645–0.448) | .724 |
| 7–8 h | 1.20 (0.75–1.66) | 0.53 (0.29–0.76) | 0.52 (0.29–0.76) | 0.49 (0.30–0.69) | 0.66 (0.35–0.96) | −0.105 (−0.174–−0.035) | 0.199 (−0.296–0.695) | 0.304 (−0.196–0.805) | .233 |
| 8–9 h | 1.25 (0.74–1.75) | 0.82 (0.48–1.17) | 1.05 (0.60–1.50) | 0.58 (0.35–0.81) | 0.51 (0.22–0.81) | −0.069 (−0.129–−0.009) | −0.166 (−0.935–0.602) | −0.097 (−0.868–0.673) | .804 |
| ≥9 h | 1.40 (0.57–2.23) | 0.41 (0.00–0.90) | 0.80 (0.15–1.45) | 0.78 (0.30–1.25) | 0.81 (0.30–1.32) | −0.051 (−0.158–0.056) | 0.846 (−0.021–1.713) | 0.897 (0.024–1.770) | .044 |
| ≥65 yr | |||||||||
| <6 h | 14.03 (11.33–16.73) | 11.00 (8.56–13.44) | 9.87 (7.22–12.52) | 10.61 (8.48–12.75) | 8.74 (6.78–10.70) | −0.042 (−0.075–−0.009) | −0.125 (−0.417–0.167) | −0.083 (−0.376–0.211) | .586 |
| 6–7 h | 14.45 (10.72–18.17) | 8.98 (6.54–11.43) | 8.01 (5.79–10.24) | 9.33 (7.35–11.32) | 7.77 (5.80–9.74) | −0.057 (−0.099–−0.015) | −0.091 (−0.416–0.235) | −0.034 (−0.362 to 0.294) | .840 |
| 7–8 h | 14.58 (11.03–18.12) | 8.41 (6.26–10.56) | 11.84 (9.06–14.62) | 8.46 (6.85–10.07) | 6.71 (5.02–8.40) | −0.049 (−0.086–−0.013) | −0.138 (−0.472–0.196) | −0.088 (−0.424–0.248) | .607 |
| 8–9 h | 14.77 (10.65–18.89) | 8.81 (6.08–11.54) | 10.25 (7.72–12.78) | 10.15 (8.23–12.07) | 7.10 (5.19–9.01) | −0.038 (−0.079–0.004) | −0.081 (−0.493–0.330) | −0.044 (−0.457–0.370) | .836 |
| ≥9 h | 20.50 (14.75–26.24) | 10.36 (6.42–14.31) | 14.70 (10.65–18.74) | 12.93 (10.36–15.50) | 10.72 (8.13–13.30) | −0.045 (−0.091–0.000) | −0.133 (−0.456–0.190) | −0.088 (−0.414–0.239) | .599 |
| BMI* | |||||||||
| Underweight | |||||||||
| <6 h | 5.40 (0.64–10.16) | 1.22 (0.00–2.96) | 2.61 (0.00–6.36) | 1.84 (0.00–4.04) | 1.48 (0.00–3.56) | −0.156 (−0.347–0.035) | −8.392 (−9.929–−6.856) | −8.236 (−9.785–−6.688) | <.001 |
| 6–7 h | 2.02 (0.14–3.90) | 0.80 (0.00–1.74) | 0.94 (0.00–2.00) | 1.28 (0.00–3.06) | 0.80 (0.00–2.35) | −0.113 (−0.332–0.106) | 0.037 (−0.233–0.307) | 0.150 (−0.197–0.497) | .397 |
| 7–8 h | 0.93 (0.00–2.01) | 0.11 (0.00–0.32) | 0.57 (0.00–1.38) | 0.47 (0.00–1.18) | 5.61 (0.08–11.13) | −0.014 (−0.261–0.234) | 0.745 (−0.332–1.822) | 0.759 (−0.347–1.865) | .178 |
| 8–9 h | 1.17 (0.00–2.70) | 2.93 (0.39–5.47) | 0.36 (0.00–1.07) | 0.59 (0.00–1.40) | 3.29 (0.00–6.99) | −0.137 (−0.271–−0.004) | 0.095 (−1.583–1.773) | 0.232 (−1.451–1.916) | .787 |
| ≥9 h | 5.18 (0.29–10.06) | 1.76 (0.00–3.86) | 2.26 (0.00–5.69) | 3.00 (0.00–6.63) | 0.90 (0.00–1.98) | −0.053 (−0.245–0.139) | 0.905 (−0.259−2.069) | 0.958 (−0.222−2.138) | .111 |
| Normal weight | |||||||||
| <6 h | 3.92 (2.46–5.39) | 3.20 (2.03–4.37) | 2.79 (1.52–4.05) | 2.48 (1.48–3.47) | 4.00 (2.55–5.45) | −0.048 (−0.106−0.011) | −0.017 (−0.516−0.483) | 0.031 (−0.472−0.534) | .904 |
| 6–7 h | 1.26 (0.69–1.82) | 0.69 (0.33–1.05) | 1.33 (0.57–2.09) | 1.64 (1.02–2.26) | 1.47 (0.80–2.14) | 0.043 (−0.027−0.112) | −0.215 (−0.776−0.345) | −0.258 (−0.822−0.306) | .370 |
| 7–8 h | 0.89 (0.53–1.24) | 0.96 (0.55–1.37) | 1.33 (0.79–1.88) | 1.17 (0.76–1.57) | 1.07 (0.64–1.49) | 0.026 (−0.026−0.077) | 0.084 (−0.398−0.567) | 0.059 (−0.427−0.544) | .812 |
| 8–9 h | 1.91 (1.14–2.69) | 1.33 (0.76–1.91) | 1.62 (0.96–2.28) | 1.58 (1.09–2.07) | 0.97 (0.55–1.38) | −0.012 (−0.068−0.044) | −0.007 (−0.556−0.541) | 0.005 (−0.546−0.555) | .987 |
| ≥9 h | 2.81 (1.34–4.27) | 1.73 (0.67–2.80) | 2.47 (1.26–3.69) | 2.72 (1.82–3.62) | 2.61 (1.34–3.88) | −0.004 (−0.066−0.058) | −0.106 (−0.691−0.479) | −0.102 (−0.691−0.486) | .734 |
| Overweight | |||||||||
| <6 h | 5.99 (3.84–8.15) | 3.17 (1.79–4.55) | 1.56 (0.68–2.44) | 3.23 (2.00–4.46) | 3.72 (2.05–5.38) | −0.078 (−0.149−−0.006) | −0.095 (−0.706−0.515) | −0.017 (−0.631−0.596) | .956 |
| 6–7 h | 2.36 (1.26–3.46) | 1.11 (0.58–1.64) | 1.41 (0.67–2.15) | 2.31 (1.48–3.13) | 1.71 (0.92–2.49) | 0.004 (−0.070−0.077) | −0.096 (−0.516−0.325) | −0.099 (−0.526−0.327) | .649 |
| 7–8 h | 2.02 (1.17–2.87) | 1.34 (0.73–1.94) | 2.01 (1.19–2.83) | 1.18 (0.74–1.61) | 1.61 (0.89–2.34) | −0.048 (−0.107−0.011) | 0.066 (−0.550−0.683) | 0.114 (−0.505−0.734) | .718 |
| 8–9 h | 2.21 (1.14–3.29) | 0.89 (0.39–1.38) | 2.54 (1.42–3.66) | 2.10 (1.35–2.86) | 1.76 (0.93–2.59) | 0.012 (−0.055−0.079) | 0.215 (−0.409−0.839) | 0.203 (−0.425−0.830) | .527 |
| ≥9 h | 4.82 (2.10–7.55) | 2.24 (0.62–3.86) | 4.30 (1.88–6.72) | 3.53 (2.06–4.99) | 3.01 (1.59–4.42) | −0.018 (−0.099−0.063) | −0.117 (−0.801−0.568) | −0.098 (−0.787−0.591) | .780 |
| Obesity | |||||||||
| <6 h | 5.72 (4.15–7.29) | 4.61 (2.95–6.27) | 4.29 (2.88–5.71) | 4.75 (3.47–6.04) | 3.22 (2.16–4.28) | −0.027 (−0.070−0.017) | 0.288 (−0.121−0.696) | 0.314 (−0.097−0.725) | .134 |
| 6–7 h | 3.68 (2.40–4.96) | 2.51 (1.71–3.31) | 2.55 (1.71–3.38) | 2.55 (1.79–3.31) | 2.27 (1.44–3.10) | −0.042 (−0.096−0.011) | 0.076 (−0.340−0.492) | 0.119 (−0.301−0.538) | .580 |
| 7–8 h | 4.72 (3.22–6.22) | 1.77 (1.11–2.44) | 2.04 (1.32–2.77) | 2.20 (1.65–2.74) | 1.50 (0.96–2.05) | −0.082 (−0.136−−0.028) | −0.194 (−0.598−0.210) | −0.112 (−0.520−0.295) | .589 |
| 8–9 h | 4.13 (2.47–5.79) | 2.36 (1.38–3.35) | 2.95 (1.79–4.11) | 2.57 (1.83–3.32) | 1.69 (0.99–2.39) | −0.045 (−0.103−0.014) | −0.223 (−0.721−0.275) | −0.178 (−0.679−0.323) | .485 |
| ≥9 h | 6.11 (4.04–8.17) | 2.54 (0.74–4.34) | 5.47 (3.36–7.58) | 4.19 (2.74–5.63) | 3.69 (2.32–5.07) | −0.024 (−0.083−0.035) | −0.059 (−0.545−0.426) | −0.035 (−0.524−0.454) | .888 |
| Region | |||||||||
| Urban | |||||||||
| <6 h | 4.41 (2.94–5.89) | 3.06 (2.03–4.09) | 3.73 (2.44–5.03) | 3.02 (1.94–4.09) | 2.86 (1.85–3.86) | −0.039 (−0.091−0.013) | −0.181 (−0.601−0.239) | −0.142 (−0.564−0.281) | .512 |
| 6–7 h | 2.39 (1.49–3.28) | 1.46 (0.98–1.94) | 1.84 (1.13–2.55) | 1.84 (1.27–2.42) | 1.52 (0.90–2.13) | −0.030 (−0.088−0.027) | −0.280 (−0.761−0.202) | −0.249 (−0.734−0.236) | .314 |
| 7–8 h | 2.72 (1.88–3.56) | 1.04 (0.64–1.43) | 1.46 (0.98–1.93) | 1.45 (1.05–1.85) | 1.38 (0.94–1.82) | −0.065 (−0.117−−0.013) | −0.112 (−0.497−0.274) | −0.047 (−0.435−0.342) | .814 |
| 8–9 h | 1.90 (1.15–2.65) | 1.25 (0.77–1.73) | 1.90 (1.19–2.62) | 1.53 (1.09–1.97) | 0.97 (0.51–1.42) | −0.016 (−0.065−0.034) | −0.198 (−0.850−0.453) | −0.183 (−0.836−0.471) | .584 |
| ≥9 h | 4.31 (2.52–6.10) | 1.25 (0.45–2.04) | 3.12 (1.72–4.51) | 2.77 (1.74–3.79) | 2.32 (1.25–3.39) | −0.020 (−0.088−0.049) | −0.413 (−0.922−0.096) | −0.393 (−0.907−0.120) | .133 |
| Rural | |||||||||
| <6 h | 5.77 (4.41–7.14) | 4.13 (2.95–5.31) | 2.48 (1.67–3.30) | 4.00 (2.97–5.02) | 4.12 (2.92–5.32) | −0.048 (−0.091−−0.005) | 0.204 (−0.180−0.587) | 0.252 (−0.134−0.637) | .201 |
| 6–7 h | 2.36 (1.62–3.11) | 1.39 (0.94–1.84) | 1.68 (1.10–2.25) | 2.39 (1.79–3.00) | 2.08 (1.46–2.71) | 0.007 (−0.041−0.055) | 0.092 (−0.230−0.413) | 0.084 (−0.241−0.410) | .610 |
| 7–8 h | 2.08 (1.33–2.82) | 1.50 (1.02–1.99) | 1.88 (1.33–2.44) | 1.54 (1.16–1.91) | 1.64 (1.08–2.20) | −0.026 (−0.073−0.021) | 0.149 (−0.237−0.535) | 0.175 (−0.214−0.564) | .379 |
| 8–9 h | 3.21 (2.18–4.24) | 1.94 (1.29–2.58) | 2.35 (1.66–3.03) | 2.34 (1.80–2.88) | 1.98 (1.30–2.66) | −0.028 (−0.075−0.018) | 0.060 (−0.380−0.500) | 0.088 (−0.354−0.531) | .696 |
| ≥9 h | 4.34 (2.82–5.85) | 2.62 (1.39–3.85) | 4.22 (2.77–5.67) | 3.83 (2.88–4.78) | 3.47 (2.38–4.57) | −0.011 (−0.058−0.036) | 0.095 (−0.326−0.516) | 0.106 (−0.317−0.529) | .624 |
| Household income† | |||||||||
| Lowest and second quartile | |||||||||
| <6 h | 4.71 (3.45–5.97) | 2.98 (2.10–3.86) | 3.57 (2.43–4.72) | 3.60 (2.63–4.56) | 4.32 (3.12–5.52) | −0.029 (−0.072−0.014) | 0.081 (−0.269−0.432) | 0.110 (−0.243−0.463) | .540 |
| 6–7 h | 2.16 (1.44–2.88) | 1.80 (1.27–2.33) | 1.91 (1.22–2.59) | 2.01 (1.43–2.59) | 2.40 (1.59–3.22) | −0.011 (−0.058−0.036) | −0.142 (−0.475−0.190) | −0.131 (−0.467−0.204) | .443 |
| 7–8 h | 2.13 (1.41–2.85) | 1.27 (0.81–1.72) | 1.47 (0.96–1.99) | 1.74 (1.32–2.15) | 1.52 (1.01–2.03) | −0.020 (−0.067−0.028) | −0.183 (−0.569−0.203) | −0.164 (−0.552−0.225) | .410 |
| 8–9 h | 3.26 (2.23–4.28) | 1.39 (0.86–1.92) | 2.10 (1.40–2.80) | 2.09 (1.59–2.59) | 1.38 (0.88–1.87) | −0.040 (−0.089−0.008) | −0.435 (−0.898−0.028) | −0.395 (−0.861−0.071) | .097 |
| ≥9 h | 3.72 (2.52–4.93) | 1.77 (0.80–2.75) | 2.89 (1.74–4.05) | 3.44 (2.45–4.42) | 3.05 (1.97–4.14) | 0.008 (−0.043−0.059) | −0.145 (−0.607−0.316) | −0.153 (−0.617−0.311) | .519 |
| Third and highest quartile | |||||||||
| <6 h | 5.59 (4.11–7.07) | 4.37 (3.06–5.69) | 2.52 (1.59–3.46) | 3.50 (2.50–4.50) | 2.70 (1.74–3.67) | −0.060 (−0.107−−0.014) | 0.016 (−0.463−0.496) | 0.077 (−0.404−0.558) | .755 |
| 6–7 h | 2.56 (1.72–3.41) | 1.05 (0.64–1.45) | 1.62 (1.10–2.15) | 2.24 (1.66–2.83) | 1.33 (0.87–1.80) | −0.010 (−0.065−0.046) | 0.134 (−0.346−0.615) | 0.144 (−0.340−0.627) | .560 |
| 7–8 h | 2.59 (1.81–3.37) | 1.28 (0.85–1.72) | 1.87 (1.33–2.40) | 1.28 (0.94–1.62) | 1.53 (1.00–2.05) | −0.065 (−0.112−−0.018) | 0.235 (−0.168−0.639) | 0.300 (−0.106−0.706) | .147 |
| 8–9 h | 1.92 (1.13–2.71) | 1.90 (1.23–2.57) | 2.19 (1.48–2.89) | 1.83 (1.34–2.33) | 1.64 (0.98–2.31) | −0.004 (−0.052−0.044) | 0.322 (−0.206−0.850) | 0.326 (−0.205−0.856) | .229 |
| ≥9 h | 5.05 (3.19–6.91) | 2.47 (1.24–3.70) | 4.90 (3.04–6.75) | 3.26 (2.25–4.26) | 2.83 (1.73–3.94) | −0.040 (−0.093−0.014) | 0.005 (−0.496−0.506) | 0.045 (−0.459−0.548) | .862 |
| Education | |||||||||
| High school or lower | |||||||||
| <6 h | 6.68 (5.33–8.03) | 5.01 (3.91–6.12) | 4.31 (3.17–5.45) | 4.23 (3.18–5.28) | 4.63 (3.43–5.83) | −0.058 (−0.094−−0.022) | −0.140 (-0.451−0.170) | −0.083 (−0.395−0.230) | .603 |
| 6–7 h | 3.56 (2.65–4.47) | 2.36 (1.79–2.93) | 2.58 (1.85–3.31) | 3.41 (2.67–4.16) | 3.32 (2.44–4.21) | −0.009 (−0.050−0.032) | 0.059 (−0.237−0.355) | 0.068 (−0.231−0.366) | .657 |
| 7–8 h | 3.79 (2.87–4.71) | 2.04 (1.49–2.58) | 2.60 (1.93–3.27) | 2.77 (2.23–3.32) | 2.87 (2.09–3.64) | −0.031 (−0.070−0.007) | 0.072 (−0.295−0.439) | 0.103 (−0.266−0.472) | .584 |
| 8–9 h | 4.07 (3.00–5.14) | 2.66 (1.93–3.38) | 3.64 (2.74–4.54) | 3.64 (2.93–4.35) | 3.05 (2.19–3.92) | −0.007 (−0.045−0.031) | −0.109 (−0.500−0.282) | −0.102 (−0.495−0.291) | .611 |
| ≥9 h | 6.51 (4.70–8.31) | 3.22 (1.93–4.51) | 5.16 (3.52–6.80) | 5.15 (4.02–6.29) | 4.52 (3.06–5.97) | −0.021 (−0.065−0.023) | 0.169 (−0.248−0.586) | 0.190 (−0.229−0.609) | .374 |
| College or higher | |||||||||
| <6 h | 1.09 (0.24–1.94) | 0.28 (0.02–0.54) | 0.81 (0.26–1.36) | 1.41 (0.46–2.36) | 1.33 (0.32–2.33) | 0.056 (−0.086−0.198) | 0.948 (0.055–1.840) | 0.892 (−0.012−1.796) | .053 |
| 6–7 h | 0.75 (0.27–1.23) | 0.28 (0.04–0.52) | 0.92 (0.44–1.40) | 0.94 (0.50–1.39) | 0.59 (0.23–0.94) | 0.055 (−0.037−0.146) | −0.454 (−1.164−0.256) | −0.509 (−1.224−0.207) | .164 |
| 7–8 h | 0.61 (0.10–1.12) | 0.39 (0.15–0.63) | 0.73 (0.38–1.07) | 0.47 (0.27–0.67) | 0.61 (0.30–0.92) | −0.016 (−0.110−0.078) | 0.078 (−0.421−0.577) | 0.094 (−0.413−0.601) | .717 |
| 8–9 h | 0.47 (0.14–0.81) | 0.43 (0.13–0.73) | 0.60 (0.17–1.04) | 0.63 (0.36–0.91) | 0.42 (0.17–0.68) | 0.029 (−0.049−0.108) | 0.584 (−0.105−1.273) | 0.555 (−0.138−1.248) | .117 |
| ≥9 h | 0.52 (0.00–1.06) | 0.30 (0.00–0.60) | 1.06 (0.26–1.85) | 1.02 (0.39–1.65) | 0.74 (0.10–1.38) | 0.079 (−0.031−0.190) | 0.797 (−0.080−1.674) | 0.718 (−0.166−1.601) | .112 |
| Smoking | |||||||||
| Smoker | |||||||||
| <6 h | 2.79 (1.51–4.07) | 2.81 (1.10–4.52) | 1.76 (0.58–2.95) | 1.69 (0.35–3.03) | 2.56 (0.69–4.42) | −0.049 (−0.147−0.049) | −0.951 (−2.025−0.123) | −0.902 (−1.981−0.177) | .101 |
| 6–7 h | 0.75 (0.33–1.17) | 0.53 (0.10–0.95) | 1.10 (0.40–1.81) | 1.76 (0.86–2.67) | 0.74 (0.11–1.37) | 0.100 (0.009–0.190) | −0.112 (−1.153−0.930) | −0.211 (−1.257−0.834) | .692 |
| 7–8 h | 1.11 (0.54–1.69) | 0.49 (0.13–0.84) | 1.23 (0.59–1.87) | 1.23 (0.71–1.76) | 1.37 (0.59–2.15) | 0.022 (−0.055−0.099) | −0.525 (−1.201−0.152) | −0.547 (−1.227−0.134) | .115 |
| 8–9 h | 2.11 (0.94–3.28) | 1.31 (0.58–2.03) | 1.43 (0.51–2.35) | 1.51 (0.73–2.30) | 0.91 (0.09–1.73) | −0.023 (−0.117−0.070) | −1.255 (−2.442−−0.068) | −1.232 (−2.423−−0.041) | .043 |
| ≥9 h | 1.88 (0.68–3.09) | 2.36 (0.41–4.31) | 1.46 (0.12–2.80) | 2.02 (0.89–3.16) | 3.20 (1.39–5.01) | 0.013 (−0.078−0.104) | 0.702 (0.038–1.367) | 0.689 (0.019–1.360) | .044 |
| Ex-smoker | |||||||||
| <6 h | 7.61 (4.66–10.56) | 6.29 (4.00–8.58) | 2.31 (0.90–3.72) | 4.17 (2.48–5.87) | 3.61 (1.93–5.28) | −0.085 (−0.152−−0.019) | 0.131 (−0.400−0.661) | 0.216 (−0.318−0.750) | .428 |
| 6–7 h | 3.54 (2.17–4.90) | 1.95 (1.11–2.79) | 2.72 (1.51–3.93) | 2.83 (1.90–3.75) | 3.00 (1.81–4.18) | −0.010 (−0.070−0.050) | 0.030 (−0.425−0.485) | 0.040 (−0.419−0.499) | .864 |
| 7–8 h | 2.81 (1.49–4.13) | 2.94 (1.86–4.03) | 3.67 (2.37–4.98) | 2.09 (1.40–2.78) | 2.22 (1.20–3.23) | −0.031 (−0.084−0.022) | 0.226 (−0.286−0.738) | 0.257 (−0.258−0.772) | .329 |
| 8–9 h | 5.17 (3.14–7.20) | 2.81 (1.58–4.05) | 3.49 (2.21–4.78) | 3.39 (2.39–4.38) | 2.35 (1.41–3.28) | −0.041 (−0.099−0.017) | 0.019 (−0.482−0.520) | 0.060 (−0.444−0.564) | .815 |
| ≥9 h | 7.46 (3.22–11.71) | 2.34 (1.00–3.68) | 4.37 (2.06–6.67) | 3.27 (2.07–4.48) | 3.06 (1.42–4.71) | −0.091 (−0.173−−0.009) | −0.813 (−1.517−−0.109) | −0.722 (−1.432−−0.013) | .046 |
| Nonsmoker | |||||||||
| <6 h | 5.27 (3.91–6.64) | 3.09 (2.17–4.00) | 3.83 (2.74–4.93) | 4.03 (3.07–4.98) | 3.81 (2.80–4.82) | −0.027 (−0.068−0.014) | 0.182 (−0.169−0.533) | 0.209 (−0.144−0.562) | .246 |
| 6–7 h | 2.82 (1.90–3.74) | 1.72 (1.21–2.23) | 1.69 (1.12–2.26) | 1.98 (1.43–2.54) | 1.64 (1.09–2.18) | −0.046 (−0.098−0.005) | −0.106 (−0.469−0.257) | −0.060 (−0.426−0.306) | .749 |
| 7–8 h | 2.83 (1.98–3.68) | 1.05 (0.68–1.41) | 1.11 (0.74–1.47) | 1.35 (1.02–1.68) | 1.26 (0.87–1.65) | −0.078 (−0.130−−0.027) | 0.078 (−0.304−0.460) | 0.156 (−0.230−0.542) | .428 |
| 8–9 h | 1.90 (1.23–2.57) | 1.37 (0.86–1.89) | 1.98 (1.32–2.64) | 1.61 (1.20–2.01) | 1.36 (0.87–1.84) | −0.014 (−0.058−0.029) | 0.205 (−0.276−0.686) | 0.219 (−0.263−0.702) | .373 |
| ≥9 h | 4.45 (2.94–5.95) | 1.79 (0.89–2.68) | 4.26 (2.91–5.61) | 3.92 (2.89–4.94) | 2.82 (1.87–3.77) | 0.002 (−0.047−0.052) | −0.149 (−0.613−0.315) | −0.151 (−0.618−0.315) | .525 |
| Diabetes mellitus‡ | |||||||||
| Non-DM group | |||||||||
| <6 h | 4.01 (3.10–4.93) | 2.70 (1.96–3.44) | 2.08 (1.50–2.66) | 2.57 (1.94–3.20) | 2.40 (1.71–3.08) | −0.051 (−0.090−−0.012) | −0.082 (−0.449−0.286) | −0.030 (−0.400−0.339) | .872 |
| 6–7 h | 2.04 (1.48–2.60) | 1.09 (0.80–1.37) | 1.26 (0.85–1.66) | 1.43 (1.06–1.80) | 1.18 (0.81–1.55) | −0.036 (−0.084−0.011) | −0.179 (−0.555−0.196) | −0.143 (−0.521−0.235) | .458 |
| 7–8 h | 1.80 (1.30–2.31) | 0.88 (0.61–1.15) | 1.10 (0.80–1.40) | 1.00 (0.76–1.23) | 1.02 (0.73–1.32) | −0.055 (−0.099−−0.010) | 0.006 (−0.271−0.282) | 0.060 (−0.220−0.340) | .673 |
| 8–9 h | 1.94 (1.31–2.57) | 1.13 (0.78–1.48) | 1.39 (0.98–1.80) | 1.39 (1.08–1.70) | 1.07 (0.67–1.47) | −0.029 (−0.075−0.017) | −0.016 (−0.524−0.491) | 0.013 (−0.497−0.523) | .961 |
| ≥9 h | 3.20 (2.13–4.26) | 1.15 (0.62–1.68) | 3.08 (2.09–4.07) | 2.32 (1.71–2.94) | 1.63 (1.00–2.25) | −0.022 (−0.071−0.027) | −0.208 (−0.745−0.329) | −0.186 (−0.725−0.354) | .500 |
| DM group | |||||||||
| <6 h | 17.95 (11.51–24.39) | 12.83 (8.38–17.28) | 11.88 (6.81–16.95) | 11.81 (8.14–15.49) | 10.28 (6.93–13.64) | −0.055 (−0.116−0.005) | 0.114 (−0.323−0.551) | 0.170 (−0.271−0.610) | .451 |
| 6–7 h | 9.29 (4.97–13.60) | 7.59 (4.07–11.11) | 9.82 (5.70–13.93) | 9.65 (7.07–12.23) | 8.64 (5.36–11.92) | −0.001 (−0.056−0.053) | 0.150 (−0.275−0.576) | 0.152 (−0.277−0.580) | .488 |
| 7–8 h | 13.52 (8.82–18.23) | 7.56 (4.51–10.61) | 12.83 (8.35–17.31) | 8.50 (6.27–10.73) | 7.28 (4.32–10.25) | −0.050 (−0.101−0.001) | 0.053 (−0.548−0.655) | 0.104 (−0.500−0.707) | .737 |
| 8–9 h | 14.49 (9.01–19.97) | 9.21 (5.29–13.13) | 13.02 (8.33–17.70) | 10.80 (7.66–13.93) | 6.12 (3.68–8.56) | −0.021 (−0.077−0.035) | −0.087 (−0.695−0.521) | −0.066 (−0.676−0.545) | .832 |
| ≥9 h | 23.77 (14.54–32.99) | 14.55 (6.84–22.27) | 10.51 (5.13–15.89) | 15.22 (10.56–19.89) | 14.87 (10.24–19.50) | −0.038 (−0.108−0.031) | 0.295 (−0.148−0.737) | 0.333 (−0.114−0.781) | .145 |
| Hypertension‡ | |||||||||
| Non-hypertension group | |||||||||
| <6 h | 2.70 (1.89–3.52) | 1.09 (0.64–1.55) | 1.11 (0.62–1.60) | 1.05 (0.57–1.54) | 1.23 (0.61–1.85) | −0.108 (−0.176−−0.040) | 0.271 (−0.382−0.925) | 0.379 (−0.278−1.036) | .258 |
| 6–7 h | 1.02 (0.66–1.39) | 0.56 (0.32–0.80) | 0.61 (0.34–0.89) | 0.76 (0.50–1.02) | 0.39 (0.18–0.60) | −0.041 (−0.102−0.021) | −0.259 (−1.006−0.488) | −0.218 (−0.968−0.531) | .568 |
| 7–8 h | 1.01 (0.69–1.34) | 0.27 (0.13–0.41) | 0.82 (0.52–1.12) | 0.39 (0.25–0.54) | 0.47 (0.28–0.67) | −0.084 (−0.140−−0.028) | 0.127 (−0.314−0.568) | 0.211 (−0.234−0.656) | .352 |
| 8–9 h | 1.43 (0.88–1.97) | 0.69 (0.42–0.97) | 0.74 (0.39–1.09) | 0.81 (0.54–1.07) | 0.55 (0.19–0.92) | −0.071 (−0.134−−0.008) | 0.260 (−0.669−1.188) | 0.331 (−0.600−1.262) | .486 |
| ≥9 h | 2.15 (1.23–3.07) | 0.63 (0.24–1.03) | 1.22 (0.50–1.94) | 1.14 (0.71–1.57) | 1.02 (0.48–1.56) | −0.058 (−0.128−0.012) | 0.054 (−0.496−0.603) | 0.112 (−0.442−0.665) | .692 |
| Hypertension group | |||||||||
| <6 h | 13.49 (10.24–16.75) | 10.88 (8.32–13.43) | 9.42 (6.88–11.96) | 10.27 (8.22–12.32) | 7.97 (6.14–9.79) | −0.040 (−0.076−−0.003) | −0.074 (−0.374−0.226) | −0.034 (−0.336−0.268) | .824 |
| 6–7 h | 10.33 (7.60–13.07) | 6.05 (4.33–7.77) | 8.23 (5.75–10.71) | 7.34 (5.70–8.99) | 6.75 (4.91–8.60) | −0.030 (−0.070−0.011) | −0.037 (−0.325−0.252) | −0.007 (−0.299−0.284) | .962 |
| 7–8 h | 10.89 (7.61–14.17) | 7.03 (5.17–8.90) | 6.86 (5.02–8.70) | 6.75 (5.39–8.12) | 5.97 (4.30–7.65) | −0.051 (−0.095−−0.007) | −0.102 (−0.459−0.255) | −0.051 (−0.411−0.308) | .781 |
| 8–9 h | 10.45 (6.92–13.98) | 7.15 (4.90–9.40) | 9.76 (7.24–12.28) | 7.76 (6.10–9.41) | 5.92 (4.24–7.60) | −0.019 (−0.064−0.026) | −0.191 (−0.566−0.185) | −0.172 (−0.550−0.206) | .373 |
| ≥9 h | 15.85 (10.32–21.39) | 10.26 (5.76–14.76) | 13.42 (9.35–17.48) | 12.15 (9.33–14.98) | 10.56 (7.77–13.36) | −0.024 (−0.075−0.027) | −0.070 (−0.459−0.319) | −0.045 (−0.437−0.347) | .820 |
| Dyslipidemia‡ | |||||||||
| Non-dyslipidemia group | |||||||||
| <6 h | 4.86 (3.85–5.87) | 2.98 (2.23–3.73) | 2.33 (1.58–3.07) | 2.92 (2.20–3.64) | 2.35 (1.62–3.09) | −0.067 (−0.106−−0.028) | 0.008 (−0.340−0.356) | 0.075 (−0.275−0.425) | .674 |
| 6–7 h | 2.13 (1.58–2.68) | 1.14 (0.83–1.44) | 1.33 (0.93–1.74) | 1.42 (1.06–1.78) | 0.93 (0.59–1.27) | −0.051 (−0.095−−0.007) | −0.381 (−0.802−0.040) | −0.330 (−0.753−0.093) | .126 |
| 7–8 h | 1.93 (1.43–2.42) | 0.99 (0.71–1.27) | 1.37 (1.02–1.72) | 0.94 (0.71–1.17) | 0.71 (0.46–0.97) | −0.071 (−0.113−−0.030) | 0.109 (−0.238−0.456) | 0.181 (−0.169−0.530) | .311 |
| 8–9 h | 2.36 (1.68–3.04) | 1.36 (0.96–1.76) | 1.65 (1.19–2.11) | 1.48 (1.15–1.81) | 0.95 (0.54–1.35) | −0.049 (−0.092−−0.007) | −0.029 (−0.635−0.577) | 0.021 (−0.587−0.628) | .947 |
| ≥9 h | 4.21 (3.03–5.38) | 1.77 (1.07–2.47) | 3.08 (2.09–4.07) | 2.38 (1.77–3.00) | 2.19 (1.48–2.90) | −0.051 (−0.096−−0.006) | 0.121 (−0.283−0.525) | 0.172 (−0.235−0.578) | .407 |
| Dyslipidemia group | |||||||||
| <6 h | 8.34 (4.36–12.32) | 8.55 (5.09–12.01) | 6.77 (4.43–9.10) | 5.98 (4.07–7.89) | 6.44 (4.48–8.41) | −0.039 (−0.097−0.019) | 0.034 (−0.395−0.463) | 0.073 (−0.360−0.505) | .741 |
| 6–7 h | 5.82 (2.67–8.97) | 4.40 (2.47–6.34) | 5.08 (3.14–7.01) | 5.56 (3.99–7.14) | 5.14 (3.49–6.79) | 0.011 (−0.053−0.074) | 0.150 (−0.205−0.504) | 0.139 (−0.221−0.499) | .449 |
| 7–8 h | 8.98 (4.13–13.83) | 4.82 (2.70–6.94) | 4.38 (2.52–6.24) | 4.62 (3.33–5.91) | 5.09 (3.53–6.66) | −0.064 (−0.135−0.008) | −0.087 (−0.506−0.332) | −0.023 (−0.449−0.402) | .915 |
| 8–9 h | 6.70 (3.06–10.34) | 5.36 (2.56–8.16) | 7.18 (4.19–10.17) | 5.05 (3.43–6.68) | 4.36 (2.79–5.92) | −0.015 (−0.076−0.046) | −0.043 (−0.532−0.446) | −0.029 (−0.522−0.465) | .910 |
| ≥9 h | 7.13 (1.67–12.58) | 6.51 (0.00–13.41) | 8.55 (4.46–12.64) | 9.80 (6.61–13.00) | 7.01 (4.33–9.68) | 0.041 (−0.045−0.126) | −0.453 (−0.941−0.035) | −0.493 (−0.988−0.002) | .051 |
| Perceived stress§ | |||||||||
| High stress | |||||||||
| <6 h | 5.50 (4.26–6.74) | 4.64 (3.51–5.76) | 3.74 (2.73–4.76) | 3.92 (2.96–4.87) | 4.01 (2.96–5.06) | −0.039 (−0.075−−0.002) | −0.078 (−0.414−0.259) | −0.039 (−0.377−0.300) | .823 |
| 6–7 h | 2.84 (2.07–3.62) | 1.51 (1.12–1.91) | 1.85 (1.35–2.35) | 2.42 (1.89–2.95) | 2.10 (1.56–2.65) | −0.014 (−0.057−0.029) | −0.121 (−0.424−0.181) | −0.107 (−0.413−0.198) | .490 |
| 7–8 h | 2.61 (1.89–3.33) | 1.40 (1.04–1.77) | 1.80 (1.36–2.24) | 1.66 (1.32–1.99) | 1.65 (1.20–2.11) | −0.042 (−0.082−−0.002) | 0.068 (−0.263−0.400) | 0.110 (−0.224−0.443) | .519 |
| 8–9 h | 2.55 (1.88–3.22) | 1.75 (1.24–2.26) | 2.35 (1.75–2.96) | 2.32 (1.88–2.75) | 1.67 (1.19–2.14) | −0.005 (−0.040−0.030) | −0.111 (−0.468−0.247) | −0.106 (−0.465−0.253) | .563 |
| ≥9 h | 4.47 (3.05–5.89) | 2.54 (1.49–3.58) | 3.99 (2.68–5.30) | 3.94 (3.03–4.84) | 3.54 (2.52–4.56) | −0.001 (−0.045−0.044) | −0.104 (−0.487−0.278) | −0.104 (−0.489−0.282) | .598 |
| Low stress | |||||||||
| <6 h | 4.49 (3.03–5.95) | 1.84 (0.99–2.70) | 1.82 (0.90–2.74) | 2.19 (1.30–3.09) | 2.29 (1.25–3.34) | −0.097 (−0.167−−0.027) | 0.437 (−0.173−1.046) | 0.533 (−0.080−1.147) | .088 |
| 6–7 h | 1.32 (0.61–2.04) | 1.19 (0.57–1.82) | 1.51 (0.61–2.41) | 1.44 (0.78–2.11) | 1.13 (0.38–1.87) | 0.002 (−0.072−0.077) | 0.340 (−0.255−0.934) | 0.337 (−0.262−0.936) | .270 |
| 7–8 h | 1.76 (1.05–2.48) | 0.88 (0.33–1.44) | 1.28 (0.65–1.91) | 1.03 (0.63–1.42) | 1.14 (0.57–1.71) | −0.055 (−0.122−0.012) | −0.073 (-0.565−0.420) | −0.018 (−0.515−0.478) | .943 |
| 8–9 h | 2.75 (1.34–4.16) | 1.16 (0.46–1.85) | 1.38 (0.66–2.10) | 0.87 (0.42–1.31) | 1.01 (0.30–1.71) | −0.005 (−0.040−0.030) | −0.111 (−0.468−0.247) | −0.106 (−0.465−0.253) | .563 |
| ≥9 h | 4.02 (2.07–5.97) | 0.90 (0.05–1.74) | 1.92 (0.31–3.54) | 1.85 (0.86–2.84) | 1.42 (0.55–2.30) | −0.090 (−0.180−0.001) | 0.027 (−0.591−0.645) | 0.116 (−0.508−0.741) | .715 |
Values in bold indicate statistical significance (P < .05).
BMI = body mass index, CI = confidence interval, CKD = chronic kidney disease, DM = diabetes mellitus, KNHANES = Korea National Health and Nutrition Examination Survey.
BMI was categorized according to the Asia-Pacific guidelines: underweight (<18.5 kg/m2), normal weight (18.5–22.9 kg/m2), overweight (23.0–24.9 kg/m2), and obesity (≥25.0 kg/m2).
Household income was calculated in quartiles based on standardized income data from the KNHANES sample households and then dichotomized into the lower half (lowest and second quartiles) and the upper half (third and highest quartiles).
Diabetes mellitus, hypertension, and dyslipidemia were defined using the corresponding physician-diagnosis variables in the KNHANES health interview (self-reported lifetime diagnosis by a physician; yes vs no).
Perceived stress was dichotomized from a single 4-point item into high (“a great deal” or “quite a lot”) and low (“a little” or “hardly any”).
β-coefficients were estimated from weighted linear regression models with CKD prevalence as the dependent variable and survey period as the independent variable, fitted separately within each stratum. β values and their confidence intervals were multiplied by 10 for ease of presentation owing to their small magnitude.
βdiff denotes the difference between the period-specific slopes for the pre-pandemic (2007–2019) and pandemic (2020–2022) periods, with its standard error obtained by error propagation from the 2 period-specific standard errors.
Figure 1.
Weighted prevalence of CKD by sleep duration category before and during the COVID-19 pandemic among Korean adults aged ≥19 years, 2007 to 2022. Bars represent weighted prevalence (%) and error bars represent 95% CIs. Sleep duration was self-reported and categorized using left-closed intervals (<6, ≥6 to <7, ≥7 to <8, ≥8 to <9, and ≥9 hours). The dashed vertical line separates the periods before the pandemic (2007–2019) and during the pandemic (2020–2022). CI = confidence interval, CKD = chronic kidney disease.
3.3. Comparison of trends before and during the COVID-19 pandemic
The difference in trend slopes between the pre-pandemic (2007–2019) and pandemic (2020–2022) periods was not statistically significant in any sleep duration category (<6 hours, βdiff 0.097 [95% CI, −0.194 to 0.389], P = .513; 6–7 hours, −0.022 [95% CI, −0.294 to 0.249], P = .871; 7–8 hours, 0.086 [95% CI, −0.197 to 0.369], P = .551; 8–9 hours, 0.008 [95% CI, −0.369 to 0.384], P = .968; ≥9 hours, −0.061 [95% CI, −0.393 to 0.272], P = .720) (Table 2). Consistent with this, period-specific odds ratios did not differ when the pandemic period was compared directly with the pre-pandemic period as the reference (<6 hours, wOR 1.01 [95% CI, 0.71–1.45], P = .939; ≥9 hours, wOR 0.93 [95% CI, 0.63–1.39], P = .737) (Table S1, Supplemental Digital Content 2). Trend stability was therefore tested within each sleep duration stratum rather than only in the overall cohort.
3.4. Sex- and age-stratified trends
Among males, prevalence in the <6 hour group declined from 3.62% [95% CI, 2.39–4.85] in 2007 to 2009 to 2.91% [95% CI, 1.92–3.89] in 2016 to 2019 and was 3.06% [95% CI, 1.99–4.13] in 2020 to 2022, and in the ≥9 hour group from 4.68% [95% CI, 2.74 to 6.62] to 2.89% [95% CI, 1.95–3.83] and then 3.02% [95% CI, 1.93–4.11]. Although these point estimates increased slightly during the pandemic period, the CIs overlapped substantially and the slope differences were not statistically significant (<6 hours, P = .483; ≥9 hours, P = .997). Among females, prevalence declined consistently in both the <6 hour (6.33% to 3.94%) and ≥9 hour (4.04%–2.89%) groups, with no significant slope difference across the pandemic threshold (P = .180 and P = .627, respectively).
The pattern diverged by age. Among adults aged 19 to 64 years, the <6 hour group consistently showed the highest prevalence, declining from 1.95% [95% CI, 1.12–2.79] in 2007 to 2009 to 0.75% [95% CI, 0.31–1.18] in 2020 to 2022. Among adults aged ≥65 years, the ≥9 hour group showed the highest prevalence, declining from 20.50% [95% CI, 14.75–26.24] to 10.72% [95% CI, 8.13–13.30]. Prevalence remained substantially higher in the older age group across all sleep duration categories. Of all strata examined, only the ≥9 hour group among adults aged 19 to 64 years showed a statistically significant slope difference across the pandemic threshold (βdiff 0.897 [95% CI, 0.024–1.770], P = .044), an isolated finding based on a low prevalence that should be interpreted cautiously.
3.5. Association between sleep duration and CKD
Table 3 presents wORs for CKD by sleep duration with 7 to 8 hours as the reference, and Figure 2 displays the corresponding fully adjusted estimates (Model 3) across subgroups. In Model 1, the odds of CKD were elevated among participants sleeping <6 hours (wOR 2.33 [95% CI, 2.03–2.67], P < .001) and ≥9 hours (wOR 2.07 [95% CI, 1.78–2.40], P < .001), with smaller but significant elevations in the adjacent 6 to 7 hour (wOR 1.18 [95% CI, 1.02 to 1.35], P = .023) and 8–9 hour (wOR 1.20 [95% CI, 1.05–1.37], P = .009) categories, describing a U-shaped association. These estimates were essentially unchanged after additional adjustment for physician-diagnosed diabetes mellitus, hypertension, and dyslipidemia (Model 2: <6 hours, wOR 2.34 [95% CI, 2.04–2.69]; ≥9 hours, wOR 2.07 [95% CI, 1.77–2.41]) and remained unchanged to 3 decimal places after further adjustment for perceived stress (Model 3), indicating that the association was not materially explained by these cardiometabolic factors or by perceived stress.
Table 3.
Weighted odds ratios and 95% CIs for CKD by sleep duration category with 7 to 8 hours as the reference in 3 sequentially adjusted models, KNHANES 2007 to 2022.
| Variables | Model 1‡ | Model 2§ | Model 3‖ | |||
|---|---|---|---|---|---|---|
| wOR (95% CI) | P-value | wOR (95% CI) | P-value | wOR (95% CI) | P-value | |
| Overall | ||||||
| <6 h | 2.33 (2.03–2.67) | <.001 | 2.34 (2.04–2.69) | <.001 | 2.34 (2.04–2.69) | <.001 |
| 6–7 h | 1.18 (1.02–1.35) | .023 | 1.18 (1.03–1.36) | .021 | 1.18 (1.03–1.36) | .021 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.20 (1.05–1.37) | .009 | 1.20 (1.05–1.37) | .009 | 1.20 (1.05–1.37) | .009 |
| ≥9 h | 2.07 (1.78–2.40) | <.001 | 2.07 (1.77–2.41) | <.001 | 2.07 (1.77–2.41) | <.001 |
| Sex | ||||||
| Male | ||||||
| <6 h | 1.79 (1.45–2.22) | <.001 | 1.82 (1.47–2.25) | <.001 | 1.82 (1.47–2.25) | <.001 |
| 6–7 h | 0.98 (0.80–1.20) | 0.823 | 0.99 (0.81–1.21) | .895 | 0.99 (0.81–1.21) | .895 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.35 (1.12–1.63) | .002 | 1.36 (1.12–1.64) | .002 | 1.36 (1.12–1.64) | .002 |
| ≥9 h | 1.88 (1.51–2.35) | <.001 | 1.95 (1.56–2.44) | <.001 | 1.95 (1.56–2.44) | <.001 |
| Female | ||||||
| <6 h | 2.87 (2.39–3.44) | <.001 | 2.86 (2.39–3.43) | <.001 | 2.86 (2.39–3.43) | <.001 |
| 6–7 h | 1.43 (1.17–1.73) | <.001 | 1.42 (1.17–1.73) | <.001 | 1.42 (1.17–1.73) | <.001 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.04 (0.85–1.28) | .679 | 1.04 (0.85–1.27) | .722 | 1.04 (0.85–1.27) | .722 |
| ≥9 h | 2.27 (1.86–2.78) | <.001 | 2.20 (1.80–2.70) | <.001 | 2.20 (1.80–2.70) | <.001 |
| Age | ||||||
| 19–64 yr | ||||||
| <6 h | 1.74 (1.29–2.35) | <.001 | 1.76 (1.30–2.37) | <.001 | 1.76 (1.30–2.37) | <.001 |
| 6–7 h | 1.28 (0.98–1.67) | .733 | 1.29 (0.99–1.69) | .064 | 1.29 (0.99–1.69) | .064 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.25 (0.97–1.61) | .080 | 1.26 (0.98–1.62) | .072 | 1.26 (0.98–1.62) | .072 |
| ≥9 h | 1.34 (0.94–1.93) | .107 | 1.32 (0.92–1.91) | .135 | 1.32 (0.92–1.91) | .135 |
| ≥65 yr | ||||||
| <6 h | 1.15 (0.98–1.34) | .087 | 1.15 (0.99–1.35) | .076 | 1.15 (0.99–1.35) | .076 |
| 6–7 h | 1.00 (0.85–1.18) | .972 | 1.00 (0.85–1.18) | .974 | 1.00 (0.85–1.18) | .974 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.06 (0.90–1.25) | .455 | 1.06 (0.90–1.25) | .479 | 1.06 (0.90–1.25) | .479 |
| ≥9 h | 1.48 (1.25–1.75) | <.001 | 1.48 (1.25–1.75) | <.001 | 1.48 (1.25–1.75) | <.001 |
| BMI* | ||||||
| Underweight | ||||||
| <6 h | 1.49 (0.56–3.94) | .427 | 1.49 (0.56–3.95) | .427 | 1.49 (0.56–3.95) | .427 |
| 6–7 h | 0.74 (0.28–1.95) | .535 | 0.74 (0.28–1.95) | .537 | 0.74 (0.28–1.95) | .537 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.13 (0.54–2.37) | .757 | 1.12 (0.53–2.36) | .761 | 1.12 (0.53–2.36) | .761 |
| ≥9 h | 1.80 (0.69–4.67) | .230 | 1.74 (0.66–4.56) | .264 | 1.74 (0.66–4.56) | .264 |
| Normal weight | ||||||
| <6 h | 2.90 (2.26–3.72) | <.001 | 2.90 (2.25–3.73) | <.001 | 2.90 (2.25–3.73) | <.001 |
| 6–7 h | 1.13 (0.85–1.50) | .399 | 1.14 (0.86–1.52) | .358 | 1.14 (0.86–1.52) | .358 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.31 (1.02–1.68) | .033 | 1.32 (1.03–1.69) | .029 | 1.32 (1.03–1.69) | .029 |
| ≥9 h | 2.27 (1.73–2.98) | <.001 | 2.33 (1.77–3.07) | <.001 | 2.33 (1.77–3.07) | <.001 |
| Overweight | ||||||
| <6 h | 2.21 (1.69–2.90) | <.001 | 2.21 (1.69–2.89) | <.001 | 2.21 (1.69–2.89) | <.001 |
| 6–7 h | 1.17 (0.89–1.54) | .250 | 1.15 (0.88–1.50) | .320 | 1.15 (0.88–1.50) | .320 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.25 (0.95–1.64) | .109 | 1.21 (0.92–1.58) | .174 | 1.21 (0.92–1.58) | .174 |
| ≥9 h | 2.22 (1.64–3.01) | <.001 | 2.23 (1.65–3.03) | <.001 | 2.23 (1.65–3.03) | <.001 |
| Obesity | ||||||
| <6 h | 2.04 (1.67–2.50) | <.001 | 2.07 (1.69–2.54) | <.001 | 2.07 (1.69–2.54) | <.001 |
| 6–7 h | 1.19 (0.97–1.46) | .093 | 1.20 (0.98–1.48) | .074 | 1.20 (0.98–1.48) | .074 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.16 (0.93–1.44) | .187 | 1.17 (0.94–1.46) | .152 | 1.17 (0.94–1.46) | .152 |
| ≥9 h | 2.00 (1.59–2.50) | <.001 | 1.96 (1.56–2.47) | <.001 | 1.96 (1.56–2.47) | <.001 |
| Region | ||||||
| Urban | ||||||
| <6 h | 2.22 (1.80–2.75) | <.001 | 2.23 (1.80–2.76) | <.001 | 2.23 (1.80–2.76) | <.001 |
| 6–7 h | 1.16 (0.94–1.42) | .168 | 1.16 (0.94–1.43) | .171 | 1.16 (0.94–1.43) | .171 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 0.99 (0.80–1.22) | .893 | 0.99 (0.80–1.23) | .919 | 0.99 (0.80–1.23) | .919 |
| ≥9 h | 1.80 (1.41–2.30) | <.001 | 1.80 (1.40–2.31) | <.001 | 1.80 (1.40–2.31) | <.001 |
| Rural | ||||||
| <6 h | 2.41 (2.02–2.89) | <.001 | 2.43 (2.03–2.91) | <.001 | 2.43 (2.03–2.91) | <.001 |
| 6–7 h | 1.19 (0.99–1.44) | .070 | 1.20 (0.99–1.45) | .062 | 1.20 (0.99–1.45) | .062 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.36 (1.14–1.62) | .001 | 1.36 (1.14–1.62) | .001 | 1.36 (1.14–1.62) | .001 |
| ≥9 h | 2.24 (1.85–2.72) | <.001 | 2.24 (1.84–2.73) | <.001 | 2.24 (1.84–2.73) | <.001 |
| Household income† | ||||||
| Lowest and second quartile | ||||||
| <6 h | 2.39 (1.97–2.91) | <.001 | 2.41 (1.98–2.92) | <.001 | 2.41 (1.98–2.92) | <.001 |
| 6–7 h | 1.26 (1.03–1.54) | .023 | 1.27 (1.04–1.55) | .020 | 1.27 (1.04–1.55) | .020 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.21 (1.00–1.46) | .050 | 1.21 (1.00–1.47) | .046 | 1.21 (1.00–1.47) | .046 |
| ≥9 h | 1.97 (1.60–2.44) | <.001 | 1.93 (1.56–2.39) | <.001 | 1.93 (1.56–2.39) | <.001 |
| Third and highest quartile | ||||||
| <6 h | 2.26 (1.86–2.74) | <.001 | 2.27 (1.87–2.76) | <.001 | 2.27 (1.87–2.76) | <.001 |
| 6–7 h | 1.10 (0.90–1.33) | .351 | 1.10 (0.90–1.33) | .350 | 1.10 (0.90–1.33) | .350 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.19 (0.98–1.44) | .080 | 1.18 (0.97–1.43) | .090 | 1.18 (0.97–1.43) | .090 |
| ≥9 h | 2.18 (1.75–2.72) | <.001 | 2.24 (1.80–2.79) | <.001 | 2.24 (1.80–2.79) | <.001 |
| Education | ||||||
| High school or lower | ||||||
| <6 h | 1.81 (1.55–2.11) | <.001 | 1.81 (1.55–2.11) | <.001 | 1.81 (1.55–2.11) | <.001 |
| 6–7 h | 1.09 (0.93–1.27) | .297 | 1.09 (0.93–1.27) | .297 | 1.09 (0.93–1.27) | .297 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.24 (1.06–1.43) | .006 | 1.23 (1.06–1.43) | .006 | 1.23 (1.06–1.43) | .006 |
| ≥9 h | 1.83 (1.54–2.16) | <.001 | 1.83 (1.54–2.16) | <.001 | 1.83 (1.54–2.16) | <.001 |
| College or higher | ||||||
| <6 h | 1.83 (1.18–2.83) | .007 | 1.83 (1.18–2.83) | .007 | 1.83 (1.18–2.83) | .007 |
| 6–7 h | 1.34 (0.94–1.91) | .107 | 1.34 (0.94–1.91) | .107 | 1.34 (0.94–1.91) | .107 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 0.97 (0.68–1.38) | .843 | 0.97 (0.68–1.38) | .843 | 0.97 (0.68–1.38) | .843 |
| ≥9 h | 1.48 (0.94–2.33) | .094 | 1.48 (0.94–2.33) | .094 | 1.48 (0.94–2.33) | .094 |
| Smoking | ||||||
| Smoker | ||||||
| <6 h | 2.07 (1.41–3.02) | <.001 | 2.09 (1.43–3.05) | <.001 | 2.09 (1.43–3.05) | <.001 |
| 6–7 h | 0.93 (0.64–1.36) | .720 | 0.91 (0.62–1.34) | .628 | 0.91 (0.62–1.34) | .628 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.31 (0.91–1.89) | .141 | 1.32 (0.92–1.90) | 0.131 | 1.32 (0.92–1.90) | .131 |
| ≥9 h | 2.14 (1.45–3.16) | <.001 | 2.15 (1.46–3.17) | <.001 | 2.15 (1.46–3.17) | <.001 |
| Ex-smoker | ||||||
| <6 h | 1.75 (1.34–2.28) | <.001 | 1.77 (1.35–2.30) | <.001 | 1.77 (1.35–2.30) | <.001 |
| 6–7 h | 1.05 (0.82–1.35) | .694 | 1.07 (0.83–1.37) | .594 | 1.07 (0.83–1.37) | .594 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.26 (0.99–1.60) | .056 | 1.26 (0.99–1.60) | .057 | 1.26 (0.99–1.60) | .057 |
| ≥9 h | 1.46 (1.08–1.95) | .013 | 1.48 (1.10–1.99) | .010 | 1.48 (1.10–1.99) | .010 |
| nonsmoker | ||||||
| <6 h | 2.87 (2.39–3.44) | <.001 | 2.87 (2.39–3.44) | <.001 | 2.87 (2.39–3.44) | <.001 |
| 6–7 h | 1.37 (1.14–1.66) | .001 | 1.37 (1.13–1.65) | .001 | 1.37 (1.13–1.65) | .001 |
| 7–8 h | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | |||
| 8–9 h | 1.16 (0.95–1.40) | .141 | 1.15 (0.95–1.39) | .155 | 1.15 (0.95–1.39) | .155 |
| ≥9 h | 2.52 (2.08–3.05) | <.001 | 2.50 (2.06–3.04) | <.001 | 2.50 (2.06–3.04) | <.001 |
The reference category for sleep duration is 7 to 8 hours in all models.
In stratified analyses, models were adjusted for all covariates except the stratifying variable.
Stratified estimates for diabetes mellitus, hypertension, dyslipidemia, and perceived stress are presented in Figure 2 and Table S1, Supplemental Digital Content 2.
Values in bold indicate statistical significance (P < .05).
BMI = body mass index, CI = confidence interval, CKD = chronic kidney disease, wOR = weighted odds ratio.
BMI was categorized according to the Asia-Pacific guidelines: underweight (<18.5 kg/m2), normal weight (18.5–22.9 kg/m2), overweight (23.0–24.9 kg/m2), and obesity (≥25.0 kg/m2).
Household income was calculated in quartiles based on standardized income data from the KNHANES sample households and then dichotomized into the lower half (lowest and second quartiles) and the upper half (third and highest quartiles).
Model 1 was adjusted for age, sex, BMI, region of residence, household income, educational attainment, and smoking status.
Model 2 was additionally adjusted for physician-diagnosed diabetes mellitus, hypertension, and dyslipidemia.
Model 3 was additionally adjusted for perceived stress. Estimates were unchanged from Model 2 to 3 decimal places.
Figure 2.
Weighted odds ratios with 95% CIs for CKD by sleep duration across subgroups among Korean adults aged ≥19 years, 2007 to 2022. The reference category is 7 to 8 hours of sleep, indicated by the vertical dotted line. Estimates are adjusted for age, sex, BMI, region of residence, household income, educational attainment, smoking status, physician-diagnosed diabetes mellitus, hypertension, and dyslipidemia, and perceived stress (Model 3), excluding the stratifying variable in each subgroup analysis. BMI = body mass index, CI = confidence interval, CKD = chronic kidney disease, DM = diabetes mellitus.
The U-shaped pattern was evident in both sexes, with a stronger association for short sleep (<6 hours) among females (wOR 2.86 [95% CI, 2.39–3.43]) than males (wOR 1.82 [95% CI, 1.47–2.25]), whereas long sleep (≥9 hours) was associated with comparable excess odds in both (males, wOR 1.95 [95% CI, 1.56–2.44]; females, wOR 2.20 [95% CI, 1.80–2.70]). The age-specific divergence observed in the prevalence data was reproduced in the adjusted models: among adults aged 19 to 64 years only short sleep was significantly associated with CKD (wOR 1.76 [95% CI, 1.30 –2.37]), with long sleep not reaching significance (wOR 1.32 [95% CI, 0.92–1.91], P = .135), whereas among adults aged ≥65 years long sleep showed the strongest association (wOR 1.48 [95% CI, 1.25–1.75]) and short sleep was not significant (wOR 1.15 [95% CI, 0.99–1.35], P = .076).
As shown in Figure 2, the U-shaped association persisted within strata defined by clinical comorbidity. Whereas Models 2 and 3 address whether the association is independent of these conditions, these stratified analyses address whether it is present within each of them. Elevated odds for both short and long sleep were observed among participants without and with physician-diagnosed diabetes mellitus (<6 hours, wOR 2.45 [95% CI, 2.07–2.89] vs 1.40 [95% CI, 1.10–1.77]; ≥9 hours, 2.02 [95% CI, 1.66–2.46] vs 1.78 [95% CI, 1.37–2.31]) and hypertension (<6 hours, 2.40 [95% CI, 1.86–3.09] vs 1.48 [95% CI, 1.25–1.74]; ≥9 hours, 2.17 [95% CI, 1.65–2.87] vs 1.83 [95% CI, 1.51–2.20]). The same pattern was seen for dyslipidemia (<6 hours, 2.74 [95% CI, 2.32–3.23] vs 1.37 [95% CI, 1.08–1.73]; ≥9 hours, 2.38 [95% CI, 1.99–2.85] vs 1.69 [95% CI, 1.28–2.25]) and in both high- and low stress strata (<6 hours, 2.50 [95% CI, 2.14–2.93] vs 2.05 [95% CI, 1.54–2.71]; ≥9 hours, 2.17 [95% CI, 1.82–2.58] vs 1.64 [95% CI, 1.15–2.33]) (Table S1, Supplemental Digital Content 2). The pattern was therefore not confined to individuals with established cardiometabolic disease. Odds ratios were smaller within the comorbid strata, which is expected given the substantially higher baseline prevalence of CKD in these groups; relative measures of association are compressed when the baseline risk is high. Across subgroups, the largest excess odds associated with extremes of sleep duration were observed among females, rural residents, those with a high school education or lower, those in the lower income half, and nonsmokers.
4. Discussion
4.1. Key finding
This study presents large-scale and long-term trends in CKD prevalence by sleep duration among 87,246 Korean adults from 2007 to 2022, and yields 5 principal findings. First, CKD prevalence was consistently higher among individuals sleeping fewer than 6 hours or 9 hours or more than among those sleeping 7 to 8 hours, with intermediate values in the adjacent categories; in fully adjusted models the odds of CKD were approximately twofold higher in both the short sleep and long sleep groups relative to the 7 to 8 hour reference. Second, this U-shaped association was not explained by comorbidity or by perceived stress levels: estimates were essentially unchanged after sequential adjustment for physician-diagnosed diabetes mellitus, hypertension, dyslipidemia, and perceived stress, and the pattern was present both among participants without and with each of these conditions. Third, short sleep was more strongly associated with CKD among females than males, whereas long sleep was associated with comparable excess odds in both sexes. Fourth, the pattern diverged by age: among adults aged 19 to 64 years only short sleep was significantly associated with CKD, whereas among those aged ≥65 years the association was confined to long sleep, and the largest excess odds were observed among females, older adults, rural residents, those with lower income or educational attainment, and nonsmokers. Fifth, CKD prevalence declined across all sleep duration categories over the study period, and the slope of this decline did not differ significantly before versus during the COVID-19 pandemic in any category.
4.2. Comparison with prior research
The association observed here is consistent with previous reports. A recent systematic review and meta-analysis of 42 studies comprising 2613,971 participants used 7 to 8 hours as the reference range and found that both short and long sleep durations were associated with an increased risk of incident CKD.[20] In a US National Health and Nutrition Examination Survey analysis of 28,239 adults, CKD prevalence was elevated among very short (≤5 hours) and long (9.0–10.9 hours) sleepers relative to those sleeping 7.0–8.9 hours, describing the same U-shaped pattern.[21] In the UK Biobank cohort of 392,218 European adults followed for a mean of 11.1 years, adherence to a healthy sleep pattern was associated in a dose-dependent manner with a lower risk of incident CKD. This pattern was defined in part by sleeping 7 to 8 hours per day; however, sleep duration was assessed as one component of a composite score rather than in isolation.[22] Beyond prevalence, a Japanese cohort of 1601 patients with established CKD found that both shorter (≤5 hours) and longer (>8 hours) sleep duration were associated with progression to end-stage kidney disease, suggesting that the association extends across the disease course.[23]
A previous Korean study provides the closest comparison. In a KNHANES analysis of 19,994 adults, both short and long sleep durations were associated with higher urinary albumin-to-creatinine ratios relative to 7 hours of sleep. This U-shaped association persisted after adjustment for diabetes, hypertension, and hypercholesterolemia, paralleling our finding that the association was independent of these comorbidities.[24] The present study extends this literature by using 5 mutually exclusive sleep categories with 7 to 8 hours as the reference, which revealed that the elevation in odds was not confined to the extremes, and by describing trends across 16 consecutive survey years in a nationally representative population. It also addresses whether the association differs by cardiometabolic comorbidity, through both sequential adjustment and stratification.
4.3. Plausible underlying mechanisms
This study found CKD prevalence to be higher among individuals sleeping fewer than 6 hours or 9 hours or more, with the lowest prevalence in the 7 to 8 hour group, a pattern that persisted after adjustment for cardiometabolic comorbidity and perceived stress. The mechanisms outlined below are drawn from prior literature and were not directly tested in the present cross-sectional analysis.
Short sleep has been linked to sympathetic activation, elevated nocturnal blood pressure, and systemic inflammation, each of which may adversely affect renal hemodynamics, and sleep loss also activates the HPA axis.[6,25] The stronger association among females may relate to sex differences in these pathways: estrogen has anti-inflammatory, antioxidant, and vasodilatory effects on the kidney,[26] which sleep deprivation–related sympathetic and inflammatory activation could plausibly attenuate, although this remains speculative and was not testable in our data.
The interpretation of long sleep is less straightforward. Prolonged sleep has often been attributed to obstructive sleep apnea, which is more prevalent in males;[27] however, hypersomnia is also a recognized feature of depressive disorders and chronic stress, and depression itself has been linked to CKD through HPA-axis activation and inflammation.[7] In the present study, long sleep was associated with comparable excess odds in both sexes, which argues against a predominantly respiratory explanation and supports considering behavioral and psychological pathways alongside sleep-disordered breathing.
The divergent age-specific patterns likely reflect different underlying processes. Among older adults, the association with long sleep is highly susceptible to reverse causation, as multimorbidity, frailty, and undiagnosed depression can lead simultaneously to prolonged sleep and reduced kidney function.[15] Creatinine-based eGFR also depends on muscle mass, so sarcopenia, which is itself associated with prolonged sleep, may lead to overclassification of CKD in this age group.[10] Sleep duration in older adults may therefore act as a marker of overall health status rather than an independent determinant of renal function, and our cross-sectional design cannot distinguish these possibilities. Because both extremes of sleep duration are also diagnostic features of depressive and anxiety disorders, sleep duration might serve as a proxy for psychological distress; the U-shaped association was nonetheless unchanged after adjustment for perceived stress and was present in both high- and low stress strata.
Finally, the sociodemographic patterns observed may reflect differences in access to care rather than in sleep physiology, as lower educational attainment, rural residence, and low income have each been associated with reduced healthcare utilization and delayed CKD diagnosis and treatment.[28–30] Smoking remains an established risk factor for chronic disease, including CKD.[31]
4.4. Clinical and policy implications
The findings of this study support targeted rather than universal approaches to CKD prevention. First, because the excess odds associated with extremes of sleep duration were greatest among older adults, rural residents, and those with lower income or educational attainment, community-based screening for reduced kidney function may be most efficiently directed toward these groups. Local health centers, which already serve as the principal point of contact for rural and older populations in Korea, are well positioned to deliver such screening and long-term monitoring.[32] Second, sleep duration is readily ascertained in a single question and could be incorporated into existing national health examinations as a simple, low-cost item for risk stratification, in line with the goals of Kidney Health Plan 2033.[3] Third, the U-shaped pattern indicates that both insufficient and excessive sleep merit attention; public health messaging that frames adequate sleep as a range rather than a minimum may therefore be more appropriate than messaging focused on sleep deprivation alone. These recommendations concern the identification of high-risk groups rather than the treatment of sleep itself, as the cross-sectional design of this study cannot establish that modifying sleep duration would reduce CKD risk.
4.5. Limitations
This study has several limitations. First, diabetes mellitus, hypertension, and dyslipidemia were ascertained from self-reported physician-diagnosis rather than from biochemical or blood pressure measurement. Undiagnosed cases were therefore classified as non-diagnosed, and information on disease duration, severity, and degree of control was unavailable, so residual confounding by these major determinants of CKD cannot be excluded. Second, although perceived stress was included as a covariate, this single item measure cannot substitute for validated instruments such as the Patient Health Questionnaire-9, which has been administered in the KNHANES only in selected years, nor does it capture obstructive sleep apnea, which was not assessed before 2019 and then only among adults aged ≥40 years. Residual confounding by clinically significant depression, anxiety, or sleep-disordered breathing therefore cannot be excluded. Third, CKD was operationalized on the basis of reduced eGFR alone; individuals with preserved eGFR and isolated albuminuria were not classified as having CKD, and prevalence estimates are consequently lower than those from studies applying the full KDIGO criteria.[16] CKD status was also ascertained from a single eGFR measurement rather than from repeated measurements over at least 3 months, which may have led to misclassification of transient reductions in eGFR. Fourth, the KNHANES contracted clinical laboratory changed during the study period, and reagent systems in 2007 to 2009 differed from those used subsequently. Serum creatinine was not among the analytes for which the KDCA issued conversion equations or advised against year-to-year comparison; nevertheless, residual analytical variation across these transitions cannot be entirely excluded as a contributor to the observed temporal trends Fifth, sleep duration was self-reported and therefore subject to recall and information bias. Other dimensions of sleep, including quality, timing, and continuity, were not assessed and may confound the observed associations.[33] The survey instrument also changed over the study period, from a single item through 2015 to separate weekday and weekend items thereafter; the shift in the distribution of sleep duration categories between the 2013–2015 and 2016 to 2019 cycles should be interpreted with this measurement change in mind. Averaging weekday and weekend sleep may additionally fail to capture the pattern of weekday sleep restriction with weekend compensation common among working adults.[34] Sixth, because the analysis is cross-sectional, it identifies associations rather than causal relationships and cannot establish whether modifying sleep duration would alter renal outcomes; this remains to be tested in prospective studies. Relatedly, CKD is a slowly progressive structural disease that develops over years to decades of cumulative exposure.[35] The 2020 to 2022 pandemic period represents a short window relative to this latency, and the absence of a significant difference in trends before versus during the pandemic should not be interpreted as evidence that the pandemic had no effect on kidney health; longer-term surveillance is required. Finally, the study population was restricted to Korean adults, which may limit generalizability, although it provides country-specific estimates for a population in which CKD epidemiology differs from that of Western countries.[36,37]
5. Conclusion
This study examined CKD prevalence trends by sleep duration from 2007 to 2022 using 16 years of nationally representative data from 87,246 Korean adults. The findings reveal a U-shaped association, with higher CKD prevalence among individuals sleeping fewer than 6 hours or 9 hours or more than among those sleeping 7 to 8 hours. This association was not attenuated by adjustment for diabetes mellitus, hypertension, dyslipidemia, or perceived stress, and was present both among participants without and with each of these conditions. Short sleep was more strongly associated with CKD among females, whereas among adults aged ≥65 years the association was confined to long sleep. Vulnerable populations included older adults, rural residents, and individuals with lower income or educational attainment. Prevalence declined across all sleep categories, with no significant difference before versus during the COVID-19 pandemic, although longer-term follow-up is required. These findings support sleep duration as a simple marker for targeted CKD screening.
Acknowledgments
This research was supported by the Ministry of Science and ICT (RS-2024-00509257 and IITP-2026-RS-2024-00438239) and the Ministry of Health & Welfare (RS-2025-02220492), Republic of Korea. This research is partially funded by the BK21 FOUR program of Graduate School, Kyung Hee University (GS-1-JO-NON-20260804). The funder of the study had no role in study design, data collection, data analysis, data interpretation or writing of the report.
Author contributions
Conceptualization: Jeongseon Oh, Yesol Yim, Hyeon Jin Kim, Sunyoung Kim, Yejun Son, Seoyoung Park, Dong Keon Yon.
Data curation: Jeongseon Oh, Yesol Yim, Sunyoung Kim, Seoyoung Park, Guillermo F. López Sánchez, Dong Keon Yon.
Formal analysis: Jeongseon Oh, Yesol Yim, Yejun Son, Jaeyu Park, Hyunjee Kim, Jaewon Kim, Selin Woo, Dong Keon Yon.
Funding acquisition: Jeongseon Oh, Yesol Yim, Dong Keon Yon.
Investigation: Jeongseon Oh, Yesol Yim, Jaeyu Park, Lee Smith, Guillermo F. López Sánchez, Dong Keon Yon.
Methodology: Jeongseon Oh, Yesol Yim, Hyeon Jin Kim, Sunyoung Kim, Seoyoung Park, Jaeyu Park, Hyunjee Kim, Lee Smith, Guillermo F. López Sánchez, Jaewon Kim, Selin Woo, Dong Keon Yon.
Project administration: Jeongseon Oh, Yesol Yim, Sunyoung Kim, Dong Keon Yon.
Visualization: Jeongseon Oh, Yesol Yim, Dong Keon Yon.
Writing – original draft: Jeongseon Oh, Yesol Yim, Dong Keon Yon.
Resources: Yesol Yim, Dong Keon Yon.
Writing – review & editing: Hyeon Jin Kim, Sunyoung Kim, Yejun Son, Seoyoung Park, Jaeyu Park, Hyunjee Kim, Lee Smith, Guillermo F. López Sánchez, Jaewon Kim, Selin Woo, Dong Keon Yon.
Software: Sunyoung Kim, Dong Keon Yon.
Supervision: Dong Keon Yon.
Validation: Dong Keon Yon.
Abbreviations:
- BMI
- body mass index
- CI
- confidence interval
- CKD
- chronic kidney disease
- COVID-19
- coronavirus disease 2019
- eGFR
- estimated glomerular filtration rate
- HPA
- hypothalamic-pituitary-adrenal
- KDCA
- Korea Disease Control and Prevention Agency
- KDIGO
- Kidney Disease Improving Global Outcomes
- KNHANES
- Korea National Health and Nutrition Examination Survey
- wOR
- weighted odds ratio
The research protocol was approved by the Institutional Review Boards of the KDCA (2007-02CON-04-P, 2008-04EXP-01-C, 2009-01CON-03-2C, 2010-02CON-21-C, 2011-02CON-06-C, 2012-01EXP-01-2C, 2013-07CON-03-4C, 2013-12EXP-03-5C, 2018-01-03-P-A, 2018-01-03-C-A, 2018-01-03-2C-A, 2018-01-03-5C-A, 2018-01-03-4C-A) and complied with local laws under the Bioethics and Safety Act (Article 2, Paragraph 1) and its Enforcement Regulation (Article 2, Paragraph 2, Item 1) from the Korean Government. Written informed consent was obtained from all participants prior to their participation. This study was conducted in accordance with the principles of the Declaration of Helsinki.
The authors have no conflicts of interest to declare.
The datasets generated during and/or analyzed during the current study are publicly available.
Supplemental Digital Content is available in the online version of this article (http://dx.doi.org/10.1097/MD.0000000000051053).
How to cite this article: Oh J, Yim Y, Kim HJ, Kim S, Son Y, Park S, Park J, Kim H, Smith L, López Sánchez GF, Kim J, Woo S, Yon DK. National trends in chronic kidney disease prevalence by sleep duration in South Korea, 2007 to 2022: A nationwide cross-sectional study. Medicine 2026;105:41(e51053).
JO, YY, HJK, SK, and SW contributed to this article equally.
Contributor Information
Jeongseon Oh, Email: dhdhwjd01@gmail.com.
Yesol Yim, Email: bearbag@naver.com.
Hyeon Jin Kim, Email: polariswon@ncerebro.com.
Sunyoung Kim, Email: polariswon@ncerebro.com.
Yejun Son, Email: dlstod9981@naver.com.
Seoyoung Park, Email: wodb980@naver.com.
Jaeyu Park, Email: wodb980@naver.com.
Hyunjee Kim, Email: polariswon@ncerebro.com.
Lee Smith, Email: Lee.Smith@aru.ac.uk.
Guillermo F. López Sánchez, Email: gfls@um.es.
Jaewon Kim, Email: polariswon@ncerebro.com.
Selin Woo, Email: dntpfls@naver.com.
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