Table 2.
Baseline characteristics of study population grouped by sleep duration.
| Sleep duration on weekdays | ||||
|---|---|---|---|---|
| ≤6 h | 6–9 h | ≥9 h | p-values | |
| (n = 1,118) | (n = 5,652) | (n = 1,499) | ||
| Demographic characteristics | ||||
| Female | 512 (45.8%) | 2,874 (50.8%) | 841 (56.1%) | *** |
| Age (year) | 48.5 (17.8) | 33.3 (24.3) | 49.1 (22.0) | *** |
| Race | *** | |||
| Mexican American | 136 (12.2%) | 848 (15.0%) | 223 (14.9%) | |
| Other Hispanic | 105 (9.39%) | 489 (8.65%) | 140 (9.34%) | |
| Non-Hispanic white | 314 (28.1%) | 1,907 (33.7%) | 538 (35.9%) | |
| Non-Hispanic black | 367 (32.8%) | 1,211 (21.4%) | 335 (22.3%) | |
| Other Race—including multi-racial | 196 (17.5%) | 1,197 (21.2%) | 263 (17.5%) | |
| Weight (kg) | 85.2 (24.9) | 65.3 (30.4) | 79.3 (22.2) | *** |
| Height (cm) | 167 (10.3) | 155 (22.0) | 165 (9.90) | *** |
| BMI (kg/m 2 ) | 30.3 (8.10) | 25.6 (8.14) | 28.9 (7.29) | *** |
| Marital status | ** | |||
| Married or living with partner | 602 (57.6%) | 1,949 (60.5%) | 701 (54.1%) | |
| Never married | 199 (19.0%) | 569 (17.7%) | 238 (18.4%) | |
| Widowed, divorced, or separated | 245 (23.4%) | 704 (21.8%) | 356 (27.5%) | |
| Comorbidities | ||||
| High blood pressure | 424 (37.9%) | 1,181 (33.4%) | 532 (35.6%) | * |
| High cholesterol | 356 (32.2%) | 1,117 (31.7%) | 495 (33.2%) | 0.60 |
| Diabetes | *** | |||
| Yes | 154 (13.8%) | 487 (8.62%) | 252 (16.8%) | |
| No | 926 (82.9%) | 5,050 (89.4%) | 1,212 (80.9%) | |
| Borderline | 37 (3.31%) | 113 (2.00%) | 34 (2.27%) | |
| Failing kidneys | 50 (4.79%) | 100 (3.10%) | 73 (5.64%) | *** |
| Anemia | 54 (4.84%) | 177 (3.13%) | 89 (5.97%) | *** |
| Congestive heart failure | 55 (5.27%) | 85 (2.64%) | 61 (4.72%) | *** |
| Coronary heart disease | 60 (5.74%) | 121 (3.76%) | 84 (6.49%) | *** |
| Stroke | 57 (5.47%) | 118 (3.67%) | 98 (7.56%) | *** |
| Chronic obstructive pulmonary disease | 71 (6.81%) | 135 (4.19%) | 87 (6.72%) | *** |
| Malignancy | 91 (8.71%) | 334 (10.4%) | 163 (12.6%) | *** |
| Renal function | ||||
| Blood Urea Nitrogen (mmol/L) | 5.36 (2.28) | 5.14 (2.04) | 5.33 (2.26) | ** |
| Creatinine, refrigerated serum (umol/L) | 82.6 (53.5) | 75.1 (33.3) | 79.6 (42.1) | *** |
| eGFR (ml/min/1.73 m2) | 95.8 (25.5) | 103 (28.8) | 95.0 (28.6) | *** |
| Uric acid (umol/L) | 330 (87.8) | 320 (87.9) | 319 (88.4) | ** |
| Albumin creatinine ratio (mg/g) | 44.0 (223) | 38.1 (294) | 59.9 (365) | 0.06 |
| Metabolites of nicotine | ||||
| Serum cotinine (ng/mL) | 75.6 (152) | 30.4 (95.9) | 49.7 (122) | *** |
| Seum hydrocotinine (ng/mL) | 30.9 (82.0) | 11.7 (41.6) | 21.4 (58.8) | *** |
*
p < 0.05,
**
p < 0.01,
***
p < 0.001 using statistical methods of ANOVA and Chi-squared test.