Table 1. Participant demographics.
| Combined | African-American | European-American | |
|---|---|---|---|
| N | 45 | 23 | 22 |
| Sex (n) | 23 F, 22 M | 57% F | 45% F |
| Age (years) | 30.5 ± 7.0 | 32.1 ± 7.1 | 28.9 ± 6.5 |
| BMI (kg/m2) | 24.2 ± 3.7 | 25.0 ± 3.9 | 23.5 ± 3.4 |
| SES | 5.4 ± 1.6 | 5.4 ± 1.5 | 5.4 ± 1.7 |
| MEQ | 53.9 ± 8.9 | 56.5 ± 8.5 | 51.3 ± 8.8* |
| MSF | 5.0 ± 1.2 | 4.8 ± 1.3 | 5.2 ± 1.1 |
| Bedtime | 00:09 ± 01:11 | 23:52 ± 01:08 | 00:27 ± 01:11 |
| Wake-time | 08:09 ± 01:11 | 07:52 ± 01:08 | 08:27 ± 01:11 |
Values shown as mean ± SD.
SES: Subjective Socioeconomic Score. MEQ: Morningness-Eveningness Questionnaire. MSF: Mid Sleep on Free days from Munich Chronotype Questionnaire score. Bedtime: scheduled baseline bedtime. Wake-time: scheduled baseline wake-time.
* Significant difference between African-Americans and European-Americans as determined by an independent t-test (p≤0.05).