Table I.
Study population characteristics by usual sleep duration at baseline, Sister Study.
| Usual Sleep Duration at Baseline
|
||||||||
|---|---|---|---|---|---|---|---|---|
| ≤ 6 hours (N=12,064) | 7 hours (N=17,737) | 8 hours (N=17,140) | ≥9 hours (N=3,513) | |||||
|
|
||||||||
| Mean | (SD) | Mean | (SD) | Mean | (SD) | Mean | (SD) | |
| Age at baseline | 55.5 | (8.7) | 55.3 | (8.8) | 55.9 | (9.2) | 56.7 | (9.6) |
| BMI at baseline | 29.0 | (6.8) | 27.6 | (6.1) | 27.2 | (5.9) | 27.6 | (6.2) |
| MET hours/week physical activity | 50.6 | (32.6) | 50.5 | (30.5) | 51.2 | (31.2) | 49.0 | (31.8) |
| Age at menarche | 12.6 | (1.6) | 12.6 | (1.5) | 12.7 | (1.5) | 12.8 | (1.6) |
| Paritya | 2.4 | (1.1) | 2.4 | (1.1) | 2.4 | (1.1) | 2.4 | (1.1) |
| Age at menopauseb | 48.6 | (6.9) | 49.4 | (6.2) | 49.6 | (6.2) | 49.5 | (6.5) |
| Pack-yearsc | 15.9 | (16.4) | 13.7 | (14.4) | 14.4 | (15.1) | 16.8 | (16.9) |
|
|
||||||||
| N | (%) | N | (%) | N | (%) | N | (%) | |
|
|
||||||||
| Non-white race | 3,407 | (28.3) | 2,531 | (14.3) | 1,897 | (11.1) | 393 | (11.2) |
| Education | ||||||||
| High school degree or less | 2,233 | (18.5) | 2,451 | (13.8) | 2,486 | (14.5) | 552 | (15.7) |
| Some college | 4,533 | (37.6) | 5,821 | (32.8) | 5,501 | (32.1) | 1,162 | (33.1) |
| College degree or higher | 5,295 | (43.9) | 9,465 | (53.4) | 9,152 | (53.4) | 1,799 | (51.2) |
| Income | ||||||||
| < 49,999 | 3,681 | (31.8) | 3,905 | (22.9) | 3,900 | (23.7) | 960 | (28.6) |
| 50,000–99,999 | 4,692 | (40.5) | 7,076 | (41.5) | 6,658 | (40.4) | 1,345 | (40.0) |
| 100,000+ | 3,211 | (27.7) | 6,092 | (35.7) | 5,909 | (35.9) | 1,055 | (31.4) |
| Marital status | ||||||||
| Never married | 833 | (6.9) | 945 | (5.3) | 816 | (4.8) | 137 | (3.9) |
| Married, living as married | 8,123 | (67.4) | 13,405 | (75.6) | 13,400 | (78.2) | 2,784 | (79.3) |
| Separated, divorced, widowed | 3,105 | (25.7) | 3,384 | (19.1) | 2,924 | (17.1) | 592 | (16.9) |
| Postmenopausal hormone useb | ||||||||
| None | 3,591 | (43.6) | 4,818 | (41.4) | 4,324 | (37.9) | 858 | (35.3) |
| Estrogen only | 2,350 | (28.5) | 3,023 | (26.0) | 3,137 | (27.5) | 720 | (29.6) |
| Progesterone or combination therapy | 2,294 | (27.9) | 3,805 | (32.7) | 3,962 | (34.7) | 855 | (35.1) |
| Birth control pills | ||||||||
| Ever | 10,035 | (83.3) | 14,988 | (84.5) | 14,410 | (84.1) | 2,921 | (83.2) |
| Alcohol consumption | ||||||||
| Never | 595 | (4.9) | 579 | (3.3) | 626 | (3.7) | 132 | (3.8) |
| Former | 2,214 | (18.4) | 2,481 | (14.0) | 2,396 | (14.0) | 570 | (16.3) |
| Current drinker, <= 1 drink/day | 8,213 | (68.2) | 12,826 | (72.4) | 11,873 | (69.4) | 2,290 | (65.3) |
| Current drinker, >1 drink day | 1,018 | (8.5) | 1,833 | (10.3) | 2,220 | (13.0) | 516 | (14.7) |
a
Among parous, N=41,253
b
Among postmenopausal at baseline, N=33,086
c
Among smokers, N=22,117