Table 1.
Baseline Characteristics of the Study Cohort, by Usual Sleep Duration, Singapore Chinese Health Study, 1993–2006a
| Characteristic | Sleep Duration, hours |
||||
| ≤5 | 6 | 7 | 8 | ≥9 | |
| No. of persons at risk | 5,450 | 13,605 | 19,179 | 15,961 | 3,849 |
| Age, years | 58.6 (0.10) | 56.6 (0.1) | 55.7 (0.1) | 55.8 (0.1) | 58.1 (0.1) |
| Women, % | 61.0 | 55.5 | 55.6 | 53.4 | 55.4 |
| No formal education, % | 34.0 | 28.1 | 26.0 | 24.8 | 29.4 |
| Smoking, % | |||||
| Current smoker | 19.3 | 19.1 | 19.0 | 20.4 | 22.4 |
| Former smoker | 11.7 | 11.3 | 9.8 | 10.9 | 13.6 |
| Never smoker | 69.0 | 69.6 | 71.2 | 68.7 | 64.0 |
| Alcohol intake, g/day | 2.2 (0.1) | 1.8 (0.1) | 1.6 (0.1) | 1.9 (0.1) | 2.2 (0.1) |
| Alcohol intake, nondrinker, % | 81.9 | 80.6 | 81.4 | 80.2 | 81.9 |
| Body mass indexb | 23.3 (0.04) | 23.1 (0.03) | 22.8 (0.02) | 23.1 (0.03) | 23.1 (0.05) |
| No weekly moderate physical activity, %c | 77.8 | 77.9 | 79.1 | 78.2 | 77.7 |
| Hypertension, % | 28.4 | 23.4 | 22.3 | 23.1 | 27.6 |
| Diabetes mellitus, % | 10.8 | 8.6 | 7.6 | 8.9 | 13.3 |
| Total calories, kcal/day | 1,515.4 (7.3) | 1,554.9 (4.7) | 1,548.8 (3.9) | 1,575.9 (4.4) | 1,580.9 (8.7) |
| Fruit intake, g/day | 190.0 (2.2) | 204.9 (1.4) | 206.3 (1.2) | 203.2 (1.3) | 192.7 (2.6) |
| Vegetable intake, g/day | 109.9 (0.8) | 109.0 (0.5) | 112.7 (0.4) | 111.4 (0.5) | 108.4 (0.8) |
| Dietary fiber intake, g/day | 12.4 (0.08) | 12.6 (0.04) | 12.8 (0.04) | 12.8 (0.04) | 12.5 (0.09) |
| Total fat intake, g/day | 43.2 (0.3) | 44.1 (0.2) | 43.7 (0.1) | 44.5 (0.2) | 44.8 (0.3) |
| Cholesterol intake, mg/day | 171.6 (1.4) | 172.8 (0.9) | 171.6 (0.7) | 176.3 (0.8) | 182.4 (1.6) |
| Weekly use of vitamin/mineral supplements, % | 6.4 | 6.4 | 6.4 | 6.1 | 5.6 |
| Women only | |||||
| Menopausal, % | 81.6 | 74.0 | 69.9 | 67.9 | 73.2 |
| Ever use of hormone replacement therapy, % | 5.8 | 5.5 | 5.1 | 5.7 | 6.0 |
a
Data presented are mean values (with standard deviations in parentheses) or row percentages, as appropriate.
b
Weight (kg)/height (m)2.
c
Moderate physical activities included brisk walking, bowling, bicycling on level ground, tai chi, or chi kung. Amounts of time spent in such activities were categorized as none, ½–3 hours/week, or ≥4 hours/week.