Table 1.
Baseline characteristics of study participants (n = 245), stratified by sleep duration at baseline: mean ± SD (median) or n (%)
| Characteristic | >7 h (n = 89) | ≤7 h (n = 156) | P valuea |
|---|---|---|---|
| Age (years) | 43.7 ± 11.3 (44) | 46.4 ± 9.8 (48) | 0.051 |
| Education | 0.540 | ||
| Some high school | 0 (0.00) | 1 (0.64) | |
| High school graduate | 10 (11.2) | 19 (12.2) | |
| Some college | 36 (40.5) | 66 (42.3) | |
| College graduate | 18 (20.2) | 31 (19.9) | |
| Some post-college education | 25 (28.1) | 39 (25.0) | |
| Race/ethnicity | 0.309 | ||
| Non-Hispanic white | 67 (75.3) | 109 (69.9) | |
| Non-Hispanic black | 5 (5.62) | 18 (11.5) | |
| Hispanic | 14 (15.7) | 24 (15.4) | |
| Other | 3 (3.37) | 5 (3.21) | |
| Household income | 0.887 | ||
| <$25,000 | 4 (4.49) | 5 (3.21) | |
| $25,000–$49,000 | 21 (23.6) | 44 (28.2) | |
| $50,000–$74,000 | 30 (33.7) | 44 (28.2) | |
| $75,000–$99,000 | 19 (21.4) | 31 (19.9) | |
| ≥$100,000 | 15 (16.9) | 32 (20.5) | |
| BMI (kg/m2) | 34.2 ± 3.5 (34) | 33.7 ± 3.2 (34) | 0.316 |
| Waist circumference (cm) | 109 ± 9.8 (109) | 108 ± 9.1 (108) | 0.852 |
| Hip circumference (cm) | 120 ± 7.4 (119) | 119 ± 8.0 (118) | 0.421 |
| Waist-to-hip ratio | 0.91 ± 0.1 (0.9) | 0.91 ± 0.1 (0.9) | 0.539 |
| Menopausal status | 0.019 | ||
| Premenopausal | 61 (68.5) | 83 (53.2) | |
| Postmenopausal | 28 (31.5) | 73 (46.8) |
a
P calculated from nonparametric rank-sum test (education and income), χ2-test (ethnicity and menopause), and t-test (age, BMI, waist circumference, hip circumference, and waist-to-hip ratio).