Table 1.
Characteristics of the study population.
| Variables (%) | Sleep duration (h/day)* | P-value | ||
|---|---|---|---|---|
| Short (≤6 h) | Average (6–8 h) | Long (>8 h) | ||
| N, N (%) | 4,801 (37.7) | 5,034 (39.6) | 2,884 (22.7) | |
| Age (years), median (Q1-Q3) | 65.0 (59.0 to 73.0) | 63.0 (56.0 to 70.0) | 64.0 (56.0 to 72.0) | <0.001 |
| Male, N (%) | 2,073 (43.2%) | 2,527 (50.2%) | 1,492 (51.7%) | <0.001 |
| Rural residency, N (%) | 3,150 (65.6%) | 2,966 (58.9%) | 1,843 (63.9%) | <0.001 |
| Education, N (%) | ||||
| Less than lower secondary education | 4,409 (91.8%) | 4,294 (85.3%) | 2,550 (88.4%) | <0.001 |
| Upper secondary & vocational training | 351 (7.3%) | 617 (12.3%) | 283 (9.8%) | |
| Tertiary | 41 (0.9%) | 123 (2.4%) | 51 (1.8%) | |
| Household income per capita (¥), median (Q1-Q3) | 3,000.0 (780.0 to 8,200.0) | 4,280.0 (1,160.0 to 10,200.0) | 3,700.0 (945.4 to 9,570.0) | <0.001 |
| BMI (Q1-Q3) | 22.60 (20.41 to 25.17) | 23.21 (20.98 to 25.74) | 23.19 (20.97 to 25.80) | <0.001 |
| Smoking, N (%) | 1,771 (36.9%) | 2,014 (40.0%) | 1,193 (41.4%) | <0.001 |
| Drinking, N (%) | 1,813 (37.8%) | 2,017 (40.1%) | 1,184 (41.1%) | <0.001 |
| BADL impairments, N (%) | 929 (19.5%) | 467 (9.4%) | 329 (11.6%) | <0.001 |
| IADL impairments, N (%) | 1,147 (24%) | 697 (13.9%) | 466 (16.2%) | <0.001 |
| Hypertension, N (%) | 1,022 (21.4%) | 1,023 (20.4%) | 639 (22.2%) | 0.150 |
| Diabetes/high blood sugar, N (%) | 218 (4.6%) | 232 (4.6%) | 145 (5.1%) | 0.614 |
| Cancer, N (%) | 39 (0.8%) | 37 (0.7%) | 21 (0.7%) | 0.879 |
| Lung disease, N (%) | 467 (9.7%) | 365 (7.3%) | 240 (8.3%) | <0.001 |
| MRD, N (%) | 61 (1.3%) | 41 (0.8%) | 36 (1.3%) | 0.058 |
| Psychiatric problems, N (%) | 59 (1.2%) | 42 (0.8%) | 23 (0.8%) | 0.074 |
| Arthritis, N (%) | 1,825 (38.1%) | 1,364 (27.1%) | 764 (26.5%) | <0.001 |
| Dyslipidemia, N (%) | 339 (7.2%) | 415 (8.4%) | 215 (7.5%) | 0.091 |
| Liver disease, N (%) | 174 (3.6%) | 125 (2.5%) | 74 (2.6%) | <0.001 |
| Kidney disease, N (%) | 251 (5.3%) | 220 (4.4%) | 107 (3.7%) | <0.006 |
| Digestive disease, N (%) | 1,185 (24.7%) | 907 (18.0%) | 500 (17.4%) | <0.001 |
| Asthma, N (%) | 197 (4.1%) | 162 (3.2%) | 100 (3.5%) | 0.057 |
MRD, memory-related disease.
*
Sleep duration was calculated as nighttime sleep duration plus daytime nap duration.