Table 1.
Characteristics of study participants at follow-up II interview by change in sleep duration from baseline (1993–1998) to follow-up II (2006–2010), the Singapore Chinese Health Study
| Change in sleep duration | P* | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Baseline | Short (≤5 hr) | Recommended (7 hr) | Long (≥9 hr) | |||||||
| Follow-up II | Short | 7 hr | Long | Short | 7 hr | Long | Short | 7 hr | Long | |
| N | 1054 | 701 | 618 | 1104 | 3659 | 2885 | 114 | 334 | 1085 | |
| Age, years | 68.8 ± 7.7 | 69.2 ± 7.3 | 73.4 ± 7.7 | 67.6 ± 7.2 | 66.2 ± 6.7 | 70.7 ± 7.5 | 70.3 ± 9.0 | 66.5 ± 6.7 | 71.0 ± 7.7 | <0.001 |
| Body mass index, kg/m2 | 23.1 ± 3.6 | 23.2 ± 3.6 | 23.1 ± 3.5 | 23.3 ± 3.6 | 23.2 ± 3.3 | 23.3 ± 3.6 | 23.1 ± 4.0 | 23.1 ± 3.7 | 23.1 ± 3.6 | 0.73 |
| Men | 374 (35.5) | 235 (33.5) | 210 (34.0) | 411 (37.2) | 1580 (43.2) | 1190 (41.3) | 46 (40.4) | 125 (37.4) | 443 (40.8) | <0.001 |
| Dialect group | <0.001 | |||||||||
| Cantonese | 512 (48.6) | 379 (54.1) | 327 (52.9) | 465 (42.1) | 1880 (51.4) | 1396 (48.4) | 54 (47.4) | 172 (51.5) | 568 (52.4) | |
| Hokkien | 542 (51.4) | 322 (45.9) | 291 (47.1) | 639 (57.9) | 1779 (48.6) | 1489 (51.6) | 60 (52.6) | 162 (48.5) | 517 (47.7) | |
| Moderate of vigorous physical activity, hr/week | <0.001 | |||||||||
| <0.5 | 91 (8.6) | 57 (8.1) | 110 (17.8) | 73 (6.6) | 249 (6.8) | 365 (12.7) | 17 (14.9) | 31 (9.3) | 168 (15.5) | |
| 0.5–4 | 127 (12.1) | 77 (11.0) | 128 (20.7) | 165 (15.0) | 559 (15.3) | 555 (19.2) | 21 (18.4) | 51 (15.3) | 193 (17.8) | |
| ≥4 | 836 (79.3) | 567 (80.9) | 380 (61.5) | 866 (78.4) | 2851 (77.9) | 1965 (68.1) | 76 (66.7) | 252 (75.5) | 724 (66.7) | |
| Level of education | <0.001 | |||||||||
| No formal education | 286 (27.1) | 225 (32.1) | 251 (40.6) | 285 (25.8) | 670 (18.3) | 902 (31.3) | 38 (33.3) | 70 (21.0) | 335 (30.9) | |
| Primary school | 473 (44.9) | 308 (43.9) | 285 (46.1) | 482 (43.7) | 1580 (43.2) | 1368 (47.4) | 53 (46.5) | 152 (45.5) | 511 (47.1) | |
| Secondary school or higher | 295 (28.0) | 168 (24.0) | 82 (13.3) | 337 (30.5) | 1409 (38.5) | 615 (21.3) | 23 (20.2) | 112 (33.5) | 239 (22.0) | |
| Smoking status | <0.001 | |||||||||
| Never | 772 (73.2) | 504 (71.9) | 422 (68.3) | 800 (72.5) | 2673 (73.1) | 1956 (67.8) | 80 (70.2) | 240 (71.9) | 708 (65.3) | |
| Former | 177 (16.8) | 107 (15.3) | 132 (21.4) | 180 (16.3) | 594 (16.2) | 575 (19.9) | 17 (14.9) | 60 (18.0) | 215 (19.8) | |
| Current | 105 (10.0) | 90 (12.8) | 64 (10.4) | 124 (11.2) | 392 (10.7) | 354 (12.3) | 17 (14.9) | 34 (10.2) | 162 (14.9) | |
| Alcohol intake | <0.001 | |||||||||
| None | 967 (91.8) | 642 (91.6) | 579 (93.7) | 1029 (93.2) | 3298 (90.1) | 2682 (93.0) | 104 (91.2) | 300 (89.8) | 981 (90.4) | |
| Weekly | 57 (5.4) | 46 (6.6) | 20 (3.2) | 52 (4.7) | 278 (7.6) | 132 (4.6) | 7 (6.1) | 24 (7.2) | 64 (5.9) | |
| Daily | 30 (2.9) | 13 (1.9) | 19 (3.1) | 23 (2.1) | 83 (2.3) | 71 (2.5) | 3 (2.6) | 10 (3.0) | 40 (3.7) | |
| Comorbidities | ||||||||||
| Hypertension | 568 (53.9) | 378 (53.9) | 404 (65.4) | 608 (55.1) | 1902 (52.0) | 1701 (59.0) | 69 (60.5) | 185 (55.4) | 637 (58.7) | <0.001 |
| Ischaemic heart disease | 98 (9.3) | 45 (6.4) | 62 (10.0) | 78 (7.1) | 187 (5.1) | 251 (8.7) | 12 (10.5) | 25 (7.5) | 76 (7.0) | <0.001 |
| Stroke | 48 (4.6) | 26 (3.7) | 55 (8.9) | 53 (4.8) | 92 (2.5) | 202 (7.0) | 8 (7.0) | 15 (4.5) | 69 (6.4) | <0.001 |
| Diabetes | 238 (22.6) | 144 (20.5) | 169 (27.4) | 231 (20.9) | 632 (17.3) | 697 (24.2) | 29 (25.4) | 75 (22.5) | 298 (27.5) | <0.001 |
| Cancer | 92 (8.7) | 47 (6.7) | 60 (9.7) | 93 (8.4) | 227 (6.2) | 269 (9.3) | 12 (10.5) | 31 (9.3) | 88 (8.1) | <0.001 |
*p-Value by ANOVA (continuous variables) or χ2-test (categorical variables).