Table 2A.
Characteristics+ and Risk Factors by Number of Hours Sleep at Phase 1
| Hours of sleep |
P-value for heterogeneity | ||||||
|---|---|---|---|---|---|---|---|
| ≤5 hours | 6 hours | 7 hours | 8 hours | ≥9 hours | |||
| Number of subjects | 587 | 2642 | 4884 | 1579 | 87 | ||
| Age, yr | 46.4 (0.2) | 44.9 (0.1) | 44.1 (0.1) | 44.0 (0.2) | 43.4 (0.6) | <0.001 | |
| Sex (% female) | 42.5 | 30.9 | 30.0 | 37.1 | 48.0 | <0.001 | |
| Employment grade (% low grade) | - Women | 52.7 | 44.8 | 45.4 | 52.4 | 70.4 | <0.001 |
| - Men | 20.3 | 10.5 | 7.0 | 9.9 | 19.2 | <0.001 | |
| Marital status (% Married) | - Women | 52.7 | 59.0 | 62.5 | 65.5 | 68.8 | 0.004 |
| - Men | 71.2 | 80.1 | 82.6 | 80.4 | 63.0 | <0.001 | |
| Current cigarette smoker (%) | - Women | 26.0 | 25.3 | 23.5 | 18.0 | 15.4 | 0.009 |
| - Men | 20.4 | 17.5 | 14.4 | 15.3 | 21.7 | 0.002 | |
| High alcohol (%) | - Women | 7.0 | 9.7 | 11.3 | 8.4 | 9.9 | 0.32 |
| - Men | 23.4 | 20.2 | 18.0 | 15.8 | 18.4 | 0.007 | |
| Little exercise (%) | - Women | 29.4 | 27.2 | 26.4 | 30.4 | 57.7 | <0.001 |
| - Men | 19.9 | 12.0 | 9.4 | 9.8 | 34.9 | <0.001 | |
| Modified GHQ score | - Women | 6.6 (0.3) | 4.2 (0.2) | 3.3 (0.1) | 2.6 (0.2) | 2.7 (0.8) | <0.001 |
| - Men | 5.5 (0.3) | 3.4 (0.1) | 2.8 (0.1) | 2.8 (0.2) | 1.9 (0.7) | <0.001 | |
| Self-rated health (% ≤ average) | - Women | 51.5 | 39.7 | 32.0 | 31.6 | 41.4 | <0.001 |
| - Men | 36.4 | 23.6 | 20.3 | 21.3 | 36.7 | <0.001 | |
| Physical Illness Indicator (% positive) | - Women | 24.6 | 20.4 | 16.7 | 17.6 | 31.8 | 0.006 |
| - Men | 27.8 | 19.8 | 19.2 | 16.6 | 12.3 | 0.001 | |
| Prevalent CHD (% positive) | - Women | 6.8 | 5.9 | 4.0 | 3.2 | 5.6 | 0.02 |
| - Men | 6.2 | 4.0 | 3.7 | 3.3 | 3.2 | 0.07 | |
| BMI (kg/m-2) | - Women | 25.3 (0.2) | 24.9 (0.1) | 24.4 (0.1) | 24.8 (0.1) | 25.1 (0.5) | 0.01 |
| - Men | 25.1 (0.2) | 24.9 (0.1) | 24.4 (0.1) | 24.4 (0.1) | 24.5 (0.5) | <0.001 | |
| Systolic blood pressure (mmHg) | - Women | 120.9 (1.0) | 120.2 (0.5) | 119.7 (0.4) | 119.0 (0.6) | 118.8 (2.1) | 0.92 |
| - Men | 125.8 (0.9) | 125.0 (0.3) | 124.2 (0.2) | 125.2 (0.5) | 125.0 (2.0) | 0.09 | |
| Diastolic blood pressure (mmHg) | - Women | 76.6 (0.7) | 75.0 (0.3) | 74.5 (0.3) | 74.7 (0.4) | 74.3 (1.6) | 0.21 |
| - Men | 79.0 (0.6) | 78.2 (0.2) | 77.5 (0.2) | 78.1 (0.3) | 79.8 (1.4) | 0.01 | |
| Cholesterol (mmol/L) | - Women | 5.97 (0.08) | 5.88 (0.04) | 5.86 (0.03) | 5.89 (0.05) | 6.02 (0.18) | 0.65 |
| - Men | 5.97 (0.07) | 5.99 (0.03) | 6.00 (0.02) | 6.02 (0.04) | 6.14 (0.16) | 0.91 | |
+
Figures are means (standard errors) for continuous measures and percentages for categorical measures. All estimates (except for age) are adjusted for age.