Table 1.
Characteristics of the study population at age 50.
| Sleep duration at age 50 | Dementia status at end of follow-up | ||||||
|---|---|---|---|---|---|---|---|
| Short: ≤6 h | Normal: 7 h | Long: ≥8 h | P | No dementia | Dementia | P | |
| N | 3149 | 3624 | 1186 | 7438 | 521 | ||
| Women | 1035 (32.9) | 1118 (30.9) | 456 (38.5) | <0.001 | 2390 (32.1) | 219 (42.0) | <0.001 |
| Ethnicity, Nmon-white | 326 (10.4) | 309 (8.5) | 163 (13.7) | <0.001 | 719 (9.7) | 79 (15.2) | <0.001 |
| Less than secondary school diploma | 1522 (48.3) | 1722 (47.5) | 575 (48.5) | 0.75 | 3509 (47.2) | 310 (59.5) | <0.001 |
| Married/cohabiting | 2296 (72.9) | 2823 (77.9) | 897 (75.6) | <0.001 | 5647 (75.9) | 369 (70.8) | 0.009 |
| Moderate alcohol drinking (1–14 units per week) | 1695 (53.8) | 2042 (56.4) | 618 (52.1) | 0.02 | 4082 (54.9) | 273 (52.4) | 0.27 |
| Current smokers | 519 (16.5) | 552 (15.2) | 168 (14.2) | 0.13 | 1138 (15.3) | 101 (19.4) | 0.013 |
| Moderate-to-vigorous physical activity (h), M (SD) | 3.3 (3.9) | 3.4 (3.5) | 3.2 (3.6) | 0.14 | 3.3 (3.7) | 3.3 (3.7) | 0.78 |
| Daily fruit and vegetable consumption | 1953 (62.0) | 2341 (64.6) | 777 (65.5) | 0.03 | 4774 (64.2) | 297 (57.0) | 0.001 |
| BMI ≥ 30 kg/m² | 414 (13.2) | 355 (9.8) | 120 (10.1) | <0.001 | 823 (11.1) | 66 (12.7) | 0.26 |
| Diabetes | 97 (3.1) | 80 (2.2) | 22 (1.9) | 0.02 | 182 (2.5) | 17 (3.3) | 0.25 |
| Hypertension | 779 (24.7) | 783 (21.6) | 288 (24.3) | 0.006 | 1700 (22.9) | 150 (28.8) | 0.002 |
| Cardiovascular disease | 105 (3.3) | 91 (2.5) | 28 (2.4) | 0.07 | 214 (2.9) | 10 (1.9) | 0.20 |
| GHQ depression | 577 (18.3) | 439 (12.1) | 143 (12.1) | <0.001 | 1070 (14.4) | 89 (17.1) | 0.09 |
| CNS medications | 169 (5.4) | 130 (3.6) | 59 (5.0) | 0.001 | 322 (4.3) | 36 (6.9) | 0.006 |
| Mental disorders before age 65 | 259 (8.2) | 231 (6.4) | 93 (7.8) | 0.01 | 541 (7.3) | 42 (8.1) | 0.51 |
Values are No. (%) unless stated otherwise. Two-sided Ps for heterogeneity were estimated using χ² test for categorical variables, and ANOVA for continuous variables by sleep duration groups and Student’s t test by dementia groups for continuous variables.
BMI body mass index, CNS central nervous system, GHQ general health questionnaire, M mean, SD standard deviation.