Table 1. Characteristics of the study population at age 50.
| Sleep duration at age 50 | |||||||
|---|---|---|---|---|---|---|---|
| Total | ≤5 hours | 6 hours | 7 hours | 8 hours | ≥9 hours | P | |
| N | 7,864 | 544 | 2,562 | 3,589 | 1,092 | 77 | |
| Sex | <0.001 | ||||||
| Men | 5,305 (67.5) | 319 (58.6) | 1,773 (69.2) | 2,491 (69.4) | 683 (62.5) | 39 (50.6) | |
| Women | 2,559 (32.5) | 225 (41.4) | 789 (30.8) | 1,098 (30.6) | 409 (37.5) | 38 (49.4) | |
| Ethnicity | <0.001 | ||||||
| White | 7,088 (90.1) | 464 (85.3) | 2,326 (90.8) | 3,286 (91.6) | 956 (87.5) | 56 (72.7) | |
| Non-white | 776 (9.9) | 80 (14.7) | 236 (9.2) | 303 (8.4) | 136 (12.5) | 21 (27.3) | |
| Education | 0.017 | ||||||
| Primary school or less | 887 (11.3) | 81 (14.9) | 288 (11.2) | 391 (10.9) | 121 (11.1) | 6 (7.8) | |
| Lower secondary school | 2,875 (36.6) | 217 (39.9) | 909 (35.5) | 1,312 (36.6) | 412 (37.7) | 25 (32.5) | |
| Higher secondary school | 1,982 (25.2) | 135 (24.8) | 681 (26.6) | 878 (24.5) | 262 (24.0) | 26 (33.8) | |
| University | 1,598 (20.3) | 85 (15.6) | 521 (20.3) | 764 (21.3) | 212 (19.4) | 16 (20.8) | |
| Higher degree | 522 (6.6) | 26 (4.8) | 163 (6.4) | 244 (6.8) | 85 (7.8) | 4 (5.2) | |
| Occupational position | <0.001 | ||||||
| Low | 1,572 (20.0) | 153 (28.1) | 480 (18.7) | 658 (18.3) | 258 (23.6) | 23 (29.9) | |
| Intermediate | 3,373 (42.9) | 253 (46.5) | 1,135 (44.3) | 1,517 (42.3) | 432 (39.6) | 36 (46.8) | |
| High | 2,919 (37.1) | 138 (25.4) | 947 (37.0) | 1,414 (39.4) | 402 (36.8) | 18 (23.4) | |
| Marital status | <0.001 | ||||||
| Married/cohabiting | 5,951 (75.7) | 344 (63.2) | 1,925 (75.1) | 2,797 (77.9) | 824 (75.5) | 61 (79.2) | |
| Single/divorced/widowed | 1,913 (24.3) | 200 (36.8) | 637 (24.9) | 792 (22.1) | 268 (24.5) | 16 (20.8) | |
| Smoking status | 0.012 | ||||||
| Never smoker | 3,885 (49.4) | 247 (45.4) | 1,272 (49.6) | 1,745 (48.6) | 574 (52.6) | 47 (61.0) | |
| Ex-smoker | 2,763 (35.1) | 192 (35.3) | 883 (34.5) | 1,303 (36.3) | 361 (33.1) | 24 (31.2) | |
| Current smoker | 1,216 (15.5) | 105 (19.3) | 407 (15.9) | 541 (15.1) | 157 (14.4) | 6 (7.8) | |
| Alcohol consumption | <0.001 | ||||||
| 0 unit/week | 1,399 (17.8) | 128 (23.5) | 419 (16.4) | 590 (16.4) | 238 (21.8) | 24 (31.2) | |
| 1–14 units/week | 4,310 (54.8) | 271 (49.8) | 1,407 (54.9) | 2,024 (56.4) | 572 (52.4) | 36 (46.8) | |
| >14 units/week | 2,155 (27.4) | 145 (26.7) | 736 (28.7) | 975 (27.2) | 282 (25.8) | 17 (22.1) | |
| Fruit and vegetable consumption | 0.010 | ||||||
| Less than once a day | 2,857 (36.3) | 233 (42.8) | 950 (37.1) | 1,271 (35.4) | 377 (34.5) | 26 (33.8) | |
| Once a day | 3,025 (38.5) | 199 (36.6) | 940 (36.7) | 1,412 (39.3) | 446 (40.8) | 28 (36.4) | |
| Twice or more a day | 1,982 (25.2) | 112 (20.6) | 672 (26.2) | 906 (25.2) | 269 (24.6) | 23 (29.9) | |
| Moderate-to-vigorous physical activity (hours), M(SD) | 3.3 (3.7) | 2.9 (4.0) | 3.3 (3.9) | 3.4 (3.5) | 3.3 (3.6) | 2.4 (3.1) | 0.009 |
| BMI (kg/m2), M(SD) | 25.5 (3.8) | 26.3 (4.8) | 25.8 (3.9) | 25.3 (3.7) | 25.1 (3.6) | 25.8 (3.5) | <0.001 |
| <18.5 kg/m2 | 78 (1.0) | 8 (1.5) | 18 (0.7) | 35 (1.0) | 16 (1.5) | 1 (1.3) | <0.001 |
| 18.5–24.9 kg/m2 | 3,906 (49.7) | 232 (42.6) | 1,185 (46.3) | 1,882 (52.4) | 575 (52.7) | 32 (41.6) | |
| 25–29.9 kg/m2 | 3,006 (38.2) | 201 (36.9) | 1,054 (41.1) | 1,323 (36.9) | 394 (36.1) | 34 (44.2) | |
| ≥30 kg/m2 | 874 (11.1) | 103 (18.9) | 305 (11.9) | 349 (9.7) | 107 (9.8) | 10 (13.0) | |
| Hypertension | 1,816 (23.1) | 150 (27.6) | 613 (23.9) | 774 (21.6) | 259 (23.7) | 20 (26.0) | 0.014 |
| Use of sleep medication | 107 (1.4) | 20 (3.7) | 47 (1.8) | 33 (0.9) | 5 (0.5) | 2 (2.6) | <0.001 |
| Prevalence of one chronic diseasea at age 50 | 647 (8.2) | 70 (12.9) | 212 (8.3) | 266 (7.4) | 84 (7.7) | 15 (19.5) | <0.001 |
a Chronic disease among diabetes, cancer, coronary heart disease, stroke, heart failure, chronic obstructive pulmonary disease, chronic kidney disease, liver disease, depression, dementia, other mental disorder, Parkinson’s disease, and arthritis/rheumatoid arthritis.
Values are No. (%) unless stated otherwise.
BMI, body mass index; M, mean; SD, standard deviation.