Table 2. Baseline characteristics of Korean adults according to self-reported sleep duration in the KNHANES 2007–2015.
| Variables | Sleep duration (hr/day) | P valuea | |||
|---|---|---|---|---|---|
| ≤ 5 | 6–8 | ≥ 9 | |||
| No. (%) | 6,149 (14.7) | 32,456 (77.6) | 3,200 (7.7) | ||
| Age, yr | 50.0 ± 0.3 | 43.0 ± 0.1 | 41.6 ± 0.4 | < 0.001 | |
| BMI, kg/m2 | 24.1 ± 0.1 | 23.6 ± 0.0 | 23.1 ± 0.1 | < 0.001 | |
| Waist circumference, cm | 82.4 ± 0.2 | 81.0 ± 0.1 | 79.8 ± 0.2 | < 0.001 | |
| Obesity | 2,166 (36.3) | 10,120 (31.3) | 917 (27.3) | < 0.001 | |
| Abdominal obesity | 1,948 (29.8) | 7,940 (23.1) | 824 (22.9) | < 0.001 | |
| Gender | < 0.001 | ||||
| Men | 2,563 (47.4) | 15,458 (54.0) | 1,370 (45.4) | ||
| Women | 3,586 (52.6) | 16,998 (46.0) | 1,830 (54.6) | ||
| Education, yr | < 0.001 | ||||
| ≤ 6 | 1,670 (20.9) | 3,614 (7.9) | 612 (13.6) | ||
| 7–12 | 2,490 (39.4) | 11,674 (34.5) | 1,147 (33.9) | ||
| ≥ 13 | 1,989 (39.8) | 17,168 (57.6) | 1,441 (52.5) | ||
| Marital status | < 0.001 | ||||
| Single | 637 (16.9) | 5,283 (23.6) | 690 (32.7) | ||
| Married | 4,165 (65.3) | 24,139 (69.1) | 2,168 (59.2) | ||
| Separated/divorced/widowed | 1,347 (17.8) | 3,034 (7.3) | 342 (8.1) | ||
| Household income | < 0.001 | ||||
| Lowest | 1,775 (22.8) | 4,821 (12.0) | 784 (20.7) | ||
| Lower middle | 1,655 (26.1) | 8,048 (25.4) | 876 (27.5) | ||
| Upper middle | 1,366 (25.4) | 9,618 (31.1) | 856 (28.5) | ||
| Highest | 1,353 (25.7) | 9,969 (31.5) | 684 (23.3) | ||
| Work schedule pattern (n=33,353) | < 0.001 | ||||
| Daytime workers | 2,094 (52.2) | 13,069 (54.1) | 971 (42.6) | ||
| Shift workers | 669 (16.7) | 3,485 (15.0) | 394 (20.9) | ||
| Other | 1,791 (31.1) | 9,797 (30.9) | 1,083 (36.5) | ||
| Alcohol use | < 0.001 | ||||
| Non-drinker | 1,384 (19.1) | 5,345 (13.7) | 683 (17.8) | ||
| Moderate drinkers, ≤ 1–4 times/mon | 3,196 (53.0) | 19,177 (60.2) | 1,765 (58.6) | ||
| Heavy drinkers, ≥ 2 times/wk | 1,569 (27.9) | 7,934 (26.1) | 752 (23.6) | ||
| Smoking | 0.386 | ||||
| Non-smoker | 3,477 (52.3) | 17,802 (50.8) | 1,739 (51.0) | ||
| Current smoker | 1,751 (32.3) | 9,746 (33.7) | 996 (34.1) | ||
| Former smoker | 921 (15.4) | 4,908 (15.5) | 465 (14.9) | ||
| Physical activity | < 0.001 | ||||
| Yes | 2,435 (38.0) | 13,224 (39.5) | 1,163 (34.8) | ||
| No | 3,714 (62.0) | 19,232 (60.5) | 2,037 (65.2) | ||
Data were summarized in number (%) or mean ± SEM, unless otherwise specified.
KNHANES = Korea National Health and Nutrition Examination Survey, BMI = body mass index, SEM = standard error of mean, ANOVA = analysis of variance.
aP value: The χ2 test or ANOVA test was used to compare categorical variables or continuous variables across the groups of sleep duration, respectively.