Table 1.
Baseline characteristics of the study population by usual sleep duration
| Characteristic | ≤ 5 h (n = 1721) | 6 h (n = 4285) | 7 h (n = 6293) | 8 h (n = 6529) | ≥ 9 h (n = 1835) | P-value |
|---|---|---|---|---|---|---|
| Fair/poor SRH, % | 23.4 ± 1.2 | 13.8 ± 0.6 | 7.5 ± 0.4 | 12.1 ± 0.5 | 23.8 ± 1.2 | < 0.0001 |
| Women, % | 53.70 ± 1.49 | 50.47 ± 0.89 | 49.89 ± 0.80 | 51.93 ± 0.78 | 56.96 ± 1.43 | 0.0001 |
| Age, years | 45.76 ± 0.47 | 45.22 ± 0.31 | 45.13 ± 0.29 | 46.27 ± 0.30 | 50.51 ± 0.67 | < 0.0001 |
| Race Categories, % | < 0.0001 | |||||
| Non-Hispanic whites | 64.18 ± 1.40 | 67.96 ± 0.92 | 72.32 ± 0.80 | 67.09 ± 0.81 | 69.69 ± 1.35 | |
| Non-Hispanic blacks | 17.41 ± 1.15 | 13.59 ± 0.67 | 8.68 ± 0.43 | 11.05 ± 0.58 | 12.09 ± 0.91 | |
| Mexican Americans | 12.41 ± 1.01 | 11.82 ± 0.60 | 12.30 ± 0.58 | 15.93 ± 0.61 | 12.94 ± 0.99 | |
| Others | 6.00 ± 0.74 | 6.63 ± 0.38 | 6.70 ± 0.37 | 5.94 ± 0.38 | 5.28 ± 0.57 | |
| Educational Categories, % | < 0.0001 | |||||
| Below high school | 19.10 ± 1.16 | 12.65 ± 0.61 | 11.28 ± 0.58 | 17.42 ± 0.63 | 24.75 ± 1.24 | |
| High school | 31.92 ± 1.39 | 27.32 ± 0.86 | 23.97 ± 0.70 | 28.26 ± 0.73 | 35.33 ± 1.47 | |
| Above high school | 48.97 ± 1.46 | 60.03 ± 0.94 | 64.75 ± 0.85 | 54.31 ± 0.80 | 39.92 ± 1.45 | |
| Smoking, % | < 0.0001 | |||||
| Never smoker | 48.85 ± 1.52 | 54.62 ± 0.93 | 60.87 ± 0.73 | 60.05 ± 0.79 | 53.79 ± 1.35 | |
| Former smoker | 19.97 ± 1.16 | 20.74 ± 0.74 | 21.50 ± 0.63 | 21.73 ± 0.65 | 24.53 ± 1.10 | |
| Current smoker | 31.17 ± 1.35 | 24.64 ± 0.85 | 17.63 ± 0.58 | 18.22 ± 0.65 | 21.68 ± 1.08 | |
| Drinking, % | < 0.0001 | |||||
| Never drinker | 19.34 ± 1.24 | 17.55 ± 0.72 | 18.12 ± 0.60 | 24.24 ± 0.70 | 27.09 ± 1.42 | |
| Former drinker | 19.02 ± 1.15 | 14.86 ± 0.66 | 12.17 ± 0.51 | 13.46 ± 0.50 | 21.20 ± 1.29 | |
| Current light drinker | 43.91 ± 1.53 | 46.28 ± 0.94 | 46.87 ± 0.79 | 41.47 ± 0.77 | 32.81 ± 1.26 | |
| Current moderate | 12.21 ± 1.00 | 15.71 ± 0.63 | 17.45 ± 0.58 | 14.72 ± 0.57 | 12.34 ± 0.88 | |
| Current heavy drinker | 5.52 ± 0.78 | 5.60 ± 0.47 | 5.38 ± 0.36 | 6.11 ± 0.38 | 6.56 ± 0.65 | |
| Body mass index Categories, % | < 0.0001 | |||||
| Normal weight | 28.73 ± 1.44 | 33.33 ± 0.91 | 37.66 ± 0.75 | 39.84 ± 0.73 | 40.09 ± 1.24 | |
| Overweight | 32.48 ± 1.45 | 35.07 ± 0.90 | 34.30 ± 0.71 | 33.28 ± 0.65 | 30.39 ± 1.24 | |
| Obese | 38.79 ± 1.49 | 31.60 ± 0.88 | 28.04 ± 0.76 | 26.88 ± 0.67 | 29.52 ± 1.24 | |
| No exercise, % | 55.25 ± 1.65 | 44.68 ± 1.04 | 40.97 ± 0.94 | 46.95 ± 0.89 | 53.64 ± 1.46 | < 0.0001 |
| Depression, % | < 0.0001 | |||||
| Absent | 93.30 ± 0.69 | 97.35 ± 0.36 | 98.86 ± 0.15 | 98.09 ± 0.21 | 95.60 ± 0.60 | |
| Chronic | 6.62 ± 0.68 | 2.59 ± 0.35 | 1.10 ± 0.14 | 1.86 ± 0.21 | 4.24 ± 0.58 | |
| not chronic | 0.08 ± 0.06 | 0.06 ± 0.04 | 0.04 ± 0.03 | 0.04 ± 0.03 | 0.16 ± 0.11 | |
| Diabetes mellitus, % | 11.73 ± 0.87 | 8.26 ± 0.53 | 6.33 ± 0.38 | 8.04 ± 0.40 | 12.83 ± 0.87 | < 0.0001 |
| Hypertension, % | 36.16 ± 1.42 | 29.39 ± 0.88 | 26.05 ± 0.72 | 28.28 ± 0.64 | 39.82 ± 1.34 | < 0.0001 |
| Cardiovascular disease. % | 8.44 ± 0.75 | 5.07 ± 0.41 | 3.59 ± 0.28 | 5.35 ± 0.30 | 14.05 ± 1.00 | < 0.0001 |
Data presented are row percentages or mean values ± standard error (SE). The P value represents difference in characteristics by usual sleep duration based on the analysis of variance or χ2 test as appropriate.