Table 1.
Comparison of baseline characteristics according to different daytime napping duration.
| Baseline Characteristics | Daytime Napping (h/day) | ||
|---|---|---|---|
| None | ≤1 | >1 | |
| N | 1234 | 904 | 482 |
| Demographic and lifestyle factors | |||
| Mean age (years) | 66.6 (5.7) | 67.1 (5.9) | 67.2 (5.8) |
| Gender, n (%) * | |||
| Male | 530 (42.9%) | 501 (55.4%) | 306 (63.5%) |
| Female | 704 (57.1%) | 403 (44.6%) | 176 (36.5%) |
| Education, n (%) * | |||
| Illiterate/no formal education | 778 (63.1%) | 487 (53.9%) | 248 (51.5%) |
| Primary school | 299 (24.2%) | 249 (27.5%) | 138 (28.6%) |
| Middle school or above | 156 (12.7%) | 168 (18.6%) | 96 (19.9%) |
| Race, n (%) * | |||
| Han ethnicity | 1101 (92.8%) | 841 (96.1%) | 437 (94.8%) |
| Other minorities | 85 (7.2%) | 34 (3.9%) | 24 (5.2%) |
| Area of residence, n (%) * | |||
| Urban | 866 (70.2%) | 592 (65.5%) | 340 (70.5%) |
| Rural | 368 (29.8%) | 312 (34.5%) | 142 (29.5%) |
| Current marital status, n (%) | |||
| Not married | 224 (18.2%) | 146 (16.2%) | 82 (17.0%) |
| Married or cohabitated | 1010 (81.8%) | 758 (83.8%) | 400 (83.0%) |
| Ever smoker, n (%) * | 489 (39.6%) | 398 (44.0%) | 255 (52.9%) |
| Ever drinker, n (%) * | 484 (39.3%) | 420 (46.5%) | 253 (52.5%) |
| Mean sleep duration (hour) * | 5.9 (2.1) | 6.2 (1.9) | 6.7 (1.9) |
| Sleep duration groups, n (%) * | |||
| ≤4 h | 389 (31.5%) | 347 (38.4%) | 221 (45.9%) |
| 4–6 h | 426 (34.5%) | 329 (36.4%) | 142 (29.5%) |
| 6–8 h | 316 (25.6%) | 166 (18.4%) | 62 (12.9%) |
| >8 h | 103 (8.3%) | 62 (6.9%) | 57 (11.8%) |
| Clinical/biochemical measures | |||
| BMI (kg/m2) * | 22.5 (3.6) | 22.9 (3.7) | 23.2 (3.6) |
| Obesity, n (%) | 79 (7.0%) | 75 (9.0%) | 38 (8.7%) |
| Waist circumference (cm) * | |||
| Male | 82.9 (9.4) | 83.6 (9.3) | 85.7 (9.6) |
| Female | 84.3 (9.9) | 86.6 (10.5) | 86.7 (11.1) |
| Central obesity, n (%) | 415 (37.3%) | 333 (40.4%) | 188 (43.1%) |
| Systolic BP (mmHg) | 133.5 (22.6) | 132.4 (21.9) | 134.6 (22.4) |
| Diastolic BP (mmHg) | 74.9 (11.9) | 73.8 (11.7) | 75.0 (11.2) |
| Plasma glucose (mmol/L) | 5.7 (0.8) | 5.7 (0.7) | 5.7 (0.8) |
| HbA1c (%) * | 5.1 (0.4) | 5.1 (0.4) | 5.2 (0.4) |
| Total cholesterol (mmol/L) | 5.0 (1.0) | 5.0 (1.0) | 4.9 (1.0) |
| Triglycerides (mmol/L) | 1.34 (0.8) | 1.32 (0.8) | 1.34 (0.8) |
| HDL-cholesterol (mmol/L) * | 1.4 (0.4) | 1.4 (0.4) | 1.3 (0.4) |
| LDL-cholesterol (mmol/L) | 3.1 (0.9) | 3.1 (0.9) | 3.0 (0.9) |
| Outcomes | |||
| DM, n (%) | 155 (12.6%) | 123 (13.6%) | 80 (16.6%) |
Abbreviation: BMI: body mass index; BP: blood pressure; HbAlc: hemoglobin A1c; HDL: high-density Lipoprotein; LDL: low-density lipoprotein; and DM: diabetes mellitus. Data were reported as mean (SD) or number (percentage). Missing data: education: N = 1; race: N = 98; drinking status: N = 2; BMI: N = 224; waist circumference: N = 247; systolic BP: 222; diastolic BP: N = 222. * p < 0.05 for difference.