Table 2.
Baseline demographic, health, and sleep characteristics of older adults by TST quartile or TIB quartile (n = 2676).
| Characteristic | TST | TIB | ||||
|---|---|---|---|---|---|---|
| Q1: < 310 min (n = 664) | IQR: 310 to < 396 min (n = 1339) | Q4: ≥ 396 min (n = 673) | Q1: < 404 min (n = 667) | IQR: 404 to < 482 min (n = 1336) | Q4: ≥ 482 min (n = 673) | |
| Age, mean (SD), y | 74.1 (5.7) | 73.2 (5.7) | 72.6 (5.6) | 73.3 (5.7) | 73.1 (5.5) | 73.6 (6.1) |
| Race, n (%) | ||||||
| Caucasian | 566 (85.2) | 1202 (89.8) | 599 (89.0) | 585 (87.7) | 1198 (89.7) | 584 (86.8) |
| Other | 98 (14.8) | 137 (10.2) | 74 (11.0) | 82 (12.3) | 138 (10.3) | 89 (13.2) |
| Women, n (%) | 310 (46.7) | 648 (48.4) | 438 (65.1) | 328 (49.2) | 694 (51.9) | 374 (55.6) |
| Body mass index, mean (SD)a | 28.0 (5.0) | 27.8 (4.6) | 27.4 (4.4) | 28.0 (4.9) | 27.7 (4.4) | 27.8 (4.8) |
| Smoking status, n (%) | ||||||
| Current | 45 (6.8) | 86 (6.4) | 41 (6.1) | 44 (6.6) | 90 (6.7) | 38 (5.6) |
| Former | 339 (51.0) | 603 (45.0) | 296 (44.0) | 327 (49.0) | 615 (46.0) | 296 (44.0) |
| Never | 280 (42.2) | 650 (48.5) | 336 (49.9) | 295 (44.2) | 631 (47.2) | 339 (50.4) |
| Apnea hypopnea index (4% oxygen desaturation), mean (SD), events/h | 13.0 (15.6) | 11.7 (13.5) | 10.2 (12.3) | 11.7 (14.3) | 11.3 (12.9) | 12.3 (15.0) |
| Sleep time with saturated oxygen below 80%, mean (SD), % time | 0.34 (4.03) | 0.13 (1.05) | 0.16 (1.27) | 0.27 (3.90) | 0.12 (1.04) | 0.26 (1.60) |
| Stroke, n (%) | 52 (7.8) | 69 (5.2) | 34 (5.1) | 50 (7.5) | 57 (4.3) | 48 (7.1) |
| Myocardial infarction, n (%) | 82 (12.5) | 127 (9.5) | 61 (9.1) | 74 (11.1) | 133 (10.0) | 63 (9.4) |
| Hypertension, n (%) | 427 (64.3) | 724 (54.1) | 334 (49.6) | 396 (59.4) | 715 (53.5) | 374 (55.6) |
| Diabetes, n (%) | 102 (15.4) | 148 (11.1) | 62 (9.2) | 90 (13.5) | 139 (10.4) | 84 (12.5) |
| PSG TST, mean (SD), min | 258.0 (44.8) | 354.7 (24.2) | 425.4 (22.1) | 284.4 (56.8) | 358.6 (49.7) | 391.8 (58.8) |
| PSG TIB, mean (SD), min | 380.3 (72.4) | 440.6 (41.5) | 484.4 (27.4) | 351.9 (43.9) | 445.2 (21.8) | 503.6 (14.3) |
| Sleep Restfulness score (1–5), mean (SD) | 2.8 (1.3) | 3.2 (1.2) | 3.5 (1.2) | 3.1 (1.3) | 3.1 (1.2) | 3.2 (1.2) |
| Stage REM sleep, mean (SD), % time | 17.1 (7.4) | 19.4 (6.0) | 19.6 (5.6) | 18.3 (7.2) | 19.1 (6.2) | 19.0 (5.8) |
| Physical Functioning Score on SF-36, mean (SD)b | 69.6 (26.2) | 73.3 (24.0) | 74.3 (23.5) | 72.8 (24.4) | 73.9 (23.7) | 69.9 (25.8) |
| Antidepressant use, n (%) | 46 (6.9) | 74 (5.5) | 47 (7.0) | 46 (6.9) | 80 (6.0) | 41 (6.1) |
| Benzodiazepine use, n (%) | 53 (8.0) | 90 (6.7) | 48 (7.1) | 54 (8.1) | 100 (7.5) | 37 (5.5) |
| Epworth Sleepiness Scale score (0–24), mean (SD) | 7.6 (4.4) | 7.6 (4.2) | 7.5 (4.5) | 7.8 (4.4) | 7.6 (4.2) | 7.4 (4.4) |
| Number of daytime naps per week, mean (SD) | 3.8 (4.5) | 3.4 (3.6) | 2.9 (3.7) | 3.7 (4.5) | 3.4 (3.8) | 3.1 (3.5) |
| Weekend-weekday difference in habitual sleep duration, mean (SD), h | 0.16 (0.63) | 0.12 (0.53) | 0.15 (0.59) | 0.18 (0.57) | 0.13 (0.56) | 0.12 (0.60) |
| Insomnia or poor sleep, n (%) | 258 (38.9) | 432 (32.3) | 222 (33.0) | 226 (33.9) | 461 (34.5) | 224 (33.3) |
SD standard deviation, PSG polysomnography, TST total sleep time, TIB time in bed, REM rapid eye movement.
aBody mass index is calculated as weight in kilograms divided by height in meters squared.
bSF-36, Short Form 36 Health Survey.