Table 2.
Mean (SD) or N (%) of sleep characteristics of study participants
| Total | White | Black | Hispanic | Chinese | Japanese | |
|---|---|---|---|---|---|---|
| Sleep duration (h) by actigraphy, M (SD)*** | 6.50 (0.99) | 6.78 (0.88)c | 6.29 (0.98)a,b | 6.50 (1.06)b | 6.22 (1.02)a | 6.09 (1.00)a |
| ≥8 h, N (%) | 71 (5.9) | 42 (7.7) | 12 (4.0) | 8 (11.0) | 5 (3.4) | 4 (3.0) |
| 6–7.99 h, N (%) | 766 (63.7) | 404 (73.7) | 173 (57.1) | 38 (52.1) | 80 (54.4) | 71 (53.8) |
| < 6 h, N (%) | 366 (30.4) | 102 (18.6) | 118 (38.9) | 27 (37.0) | 62 (42.2) | 57 (43.2) |
| Wake after sleep onset (min), M (SD)*** | 51.61 (23.26) | 48.57 (22.33)a | 59.60 (26.48)b | 55.89 (22.44)b | 49.19 (21.00)a | 46.22 (16.27)a |
| Diary rating of sleep quality, M (SD)*** | 3.62 (0.61) | 3.69 (0.58)a | 3.60 (0.64)a | 3.61 (0.64)a | 3.52 (0.61)a | 3.51 (0.65)a |
Higher score on diary sleep quality is better. Different superscripts indicate different means from paired post hoc tests; no paired comparisons were conducted for sleep duration categories. No covariates were included in these comparisons.
***p < 0.001 from ANOVA.