Table 2.
Characteristics of the population by nighttime-daytime sleep patterns
| Variables | Short nighttime sleep with daytime napping | Short nighttime sleep without daytime napping | Long nighttime sleep with daytime napping | Long nighttime sleep without daytime napping | P-value |
|---|---|---|---|---|---|
| No. subjects (%) | 1314 | 938 | 1427 | 1061 | |
| Age (years) | 74.56 (6.89) | 73.92 (6.91) | 74.17 (7.21) | 72.95 (7.09) | < 0.001 |
| Female (%) | 715 (56.2) | 591 (66.0) | 717 (52.0) | 521 (50.7) | < 0.001 |
| BMI (kg/m2) | 24.17 (4.81) | 24.12 (3.41) | 24.42 (4.24) | 28.78 (94.06) | 0.055 |
| Physical activity (Met·h/week) | 37.88 (113.01) | 40.65 (154.42) | 33.65 (67.96) | 43.41 (233.33) | 0.549 |
| Number of family members | 2.61 (1.31) | 2.54 (1.40) | 2.49 (1.15) | 2.64 (1.24) | 0.014 |
| Family income (yuan, RMB) | 7326.32 (15,985.04) | 6459.34 (5168.58) | 7230.51 (9437.45) | 7284.66 (9693.30) | 0.344 |
| Smoking status (%) | < 0.001 | ||||
| Non-smoker | 1050 (85.4) | 758 (85.5) | 1091 (81.3) | 777 (78.5) | |
| Ex-smoker | 94 (7.6) | 78 (8.8) | 139 (10.4) | 124 (12.5) | |
| Current smoker | 84 (6.8) | 51 (5.7) | 112 (8.3) | 89 (9.0) | |
| Alcohol consumption (%) | 0.784 | ||||
| None or < once/month | 1144 (89.4) | 816 (88.6) | 1239 (88.2) | 917 (88.1) | |
| Past alcohol drinker (>once/month) | 113 (8.8) | 88 (9.6) | 137 (9.8) | 110 (10.6) | |
| Current alcohol drinker (>once/month) | 22 (1.7) | 17 (1.8) | 27 (1.9) | 14 (1.3) | |
| Any of chronic diseases (%) | 965 (85.6) | 720 (86.2) | 1047 (83.6) | 725 (79.8) | 0.001 |
| Diabetes (%) | 201 (17.0) | 162 (18.9) | 261 (20.1) | 190 (19.8) | 0.233 |
| CVD (%) | 747 (56.8) | 530 (56.5) | 813 (57.0) | 535 (50.4) | 0.003 |
| Dyslipidemia (%) | 361 (27.5) | 273 (29.1) | 393 (27.5) | 245 (23.1) | 0.014 |
| Cancer (%) | 58 (5.1) | 35 (4.1) | 43 (3.4) | 39 (4.2) | 0.231 |
| Arthritis (%) | 237 (18.0) | 152 (16.2) | 205 (14.4) | 102 (9.6) | < 0.001 |
Unless indicated otherwise, data are given as the mean ± SD or as number and percentages
Abbreviations: BMI body mass index, PAL physical activity level