Table 1.
Age-standardized characteristics of the study population by sleep-quality score
| The Women’s Health Initiative (1994) |
The Nurses’ Health Study II (2013) |
|||||||
|---|---|---|---|---|---|---|---|---|
| Quartiles of sleep-quality score |
||||||||
| 0 to 1 | 2 to 3 | 4 to 5 | 6 to 12 | 0 to 2 | 3 to 4 | 5 to 6 | 7 to 12 | |
| N | 395 | 604 | 451 | 506 | 51 | 63 | 42 | 53 |
| Age, years | 67.2 (7.5) | 67.4 (6.4) | 67.5 (6.7) | 66.2 (7.1) | 60.8 (4.2) | 60.4 (4.4) | 61.2 (3.6) | 60.2 (3.8) |
| Non-White, % | 21 | 21 | 17 | 15 | 2 | 2 | 5 | 6 |
| BMI, kg/m2 | 27.5 (5.9) | 28.0 (5.8) | 28.4 (5.7) | 28.6 (5.9) | 25.8 (7.0) | 25.1 (4.6) | 27.4 (6.4) | 26.8 (5.4) |
| Current smokers, % | 12 | 12 | 9 | 13 | 2 | 7 | 0 | 2 |
| Physical activity, MET-hrs/week | 11.9 (12.8) | 12.0 (13.6) | 10.4 (12.1) | 10.0 (11.5) | 26.7 (21.9) | 32.6 (29.4) | 33.6 (28.0) | 21.1 (19.4) |
| Hypertension, % | 37 | 40 | 42 | 48 | 28 | 32 | 31 | 38 |
| Elevated depressive symptoms, % | 3 | 9 | 16 | 29 | 0 | 9 | 25 | 47 |
| Diet quality score | 67.9 (10.6) | 67.5 (11.0) | 66.4 (11.7) | 65.7 (10.8) | 67.6 (10.7) | 71.6 (12.8) | 67.0 (14.1) | 69.2 (13.2) |
| Caffeine intake, mg/day | 174 (140) | 166 (148) | 161 (132) | 178 (146) | 179 (112) | 165 (129) | 166 (135) | 200 (188) |
| Alcohol drinking, g/day | 4.6 (10.2) | 5.1 (11.3) | 4.7 (9.6) | 5.6 (13.9) | 9.7 (14.5) | 8.1 (10.6) | 8.5 (14.1) | 6.6 (8.2) |
| Current statin use, % | 8 | 10 | 10 | 13 | 16 | 18 | 29 | 34 |
| Other lipid-lowering drug use, % | 1 | 1 | 2 | 3 | 0 | 4 | 0 | 9 |
| Current aspirin use, % | 23 | 24 | 26 | 31 | 26 | 33 | 29 | 41 |
| Current hormone therapy, % | 1 | 1 | 2 | 1 | 20 | 26 | 24 | 30 |
| Sleep-medication use, % | 1 | 8 | 29 | 67 | 9 | 33 | 47 | 84 |
| Sleep duration, hours | 7.1 (1.1) | 7.0 (1.0) | 6.7 (1.0) | 6.2 (1.2) | 7.1 (0.8) | 7.1 (1.0) | 6.9 (0.8) | 6.3 (1.1) |
| Habitual snoring, % | 33 | 37 | 41 | 51 | 20 | 17 | 33 | 41 |