Table 1.
Demographic and health characteristics of the study population at baseline.
| Napping duration groups (categorized by sleep daytime napping in Wave 1) | ||||||
|---|---|---|---|---|---|---|
| 0 min (670) | 0–30 min (1,032) | 30–90 min (481) | >90 min (1,841) | All (4,024) | P-value | |
| Continuous variables, mean (SD) | ||||||
| Age, years | 66.70 (5.79) | 66.73 (5.77) | 67.21 (6.05) | 67.23 (6.11) | 66.90 (5.89) | 0.069 |
| BMI, kg/m2 | 22.72 (4.09) | 23.28 (4.20) | 23.27 (3.79) | 23.31 (3.84) | 23.02 (4.01) | <0.001 |
| Sleep duration per night, hours | 5.94 (2.07) | 6.11 (1.91) | 5.34 (1.81) | 6.72 (1.94) | 6.16 (1.98) | <0.001 |
| Baseline cognition score | 11.80 (6.31) | 13.20 (6.12) | 12.70 (6.56) | 12.70 (6.10) | 12.37 (6.34) | <0.001 |
| Categorical variables, n (%) | ||||||
| Gender (male) | 316 (47.2) | 592 (57.4) | 290 (60.3) | 751 (40.8) | 1,949 (48.4) | <0.001 |
| High level of education | 36 (5.4) | 70 (6.8) | 26 (5.4) | 73 (4.0) | 205 (5.1) | 0.011 |
| Physical activity | ||||||
| Vigorous physical activities | 140 (20.9) | 226 (21.9) | 97 (20.2) | 444 (24.1) | 907 (22.5) | 0.141 |
| Moderate physical activities | 185 (27.6) | 277 (26.8) | 116 (24.1) | 531 (28.8) | 1,109 (27.6) | 0.200 |
| Walking | 316 (47.2) | 460 (44.6) | 183 (38.0) | 855 (46.4) | 1,814 (45.1) | 0.006 |
| Depression symptoms | 350 (52.2) | 523 (50.7) | 234 (48.6) | 894 (48.6) | 2,001 (49.7) | 0.349 |
| Taking sleeping pills | 15 (2.2) | 14 (1.4) | 10 (2.1) | 23 (1.2) | 62 (1.5) | 0.228 |
| Current smoking | 341 (50.9) | 559 (54.2) | 282 (58.6) | 1,045 (56.8) | 2,227 (55.3) | 0.023 |
| Current alcohol use | 529 (79.0) | 307 (29.7) | 134 (27.9) | 383 (20.8) | 965 (24.0) | <0.001 |
| Medical history | ||||||
| Hypertension | 208 (31.0) | 334 (32.4) | 154 (32.0) | 462 (25.1) | 1,158 (28.8) | <0.001 |
| Dyslipidemia | 80 (11.9) | 140 (13.6) | 54 (11.2) | 135 (7.3) | 409 (10.2) | <0.001 |
| Diabetes | 67 (10.0) | 81 (7.8) | 27 (5.6) | 72 (3.9) | 247 (6.1) | <0.001 |
| Cancer | 8 (1.2) | 10 (1.0) | 1 (0.2) | 13 (0.7) | 32 (0.8) | 0.258 |
| Chronic lung diseases | 79 (11.8) | 155 (15.0) | 67 (13.9) | 210 (11.4) | 511 (12.7) | 0.030 |
| Liver disease | 25 (3.7) | 40 (3.9) | 19 (4.0) | 72 (3.9) | 156 (3.9) | 0.997 |
| Heart problems | 117 (17.5) | 166 (16.1) | 70 (14.6) | 229 (12.4) | 582 (14.5) | 0.004 |
| Stroke | 23 (3.4) | 35 (3.4) | 15 (3.1) | 36 (2.0) | 109 (2.7) | 0.059 |
| Kidney disease | 48 (7.2) | 69 (6.7) | 25 (5.2) | 123 (6.7) | 265 (6.6) | 0.590 |
| Stomach or other digestive disease | 157 (23.4) | 242 (23.4) | 117 (24.3) | 456 (24.8) | 972 (24.2) | 0.836 |
| Emotional, nervous, or psychiatric problems | 15 (2.2) | 13 (1.3) | 9 (1.9) | 22 (1.2) | 59 (1.5) | 0.207 |
| Memory-related disease | 11 (1.6) | 20 (1.9) | 14 (2.9) | 29 (1.6) | 74 (1.8) | 0.265 |
| Arthritis or rheumatism | 271 (40.4) | 382 (37.0) | 182 (37.8) | 759 (41.2) | 1,594 (39.6) | 0.125 |
| Asthma | 29 (4.3) | 54 (5.2) | 31 (6.4) | 86 (4.7) | 200 (5.0) | 0.348 |
BMI, body mass index. The bold values provided in table means that P < 0.05.