Table 2 Circadian period (τ), baseline circadian phase, sleep schedule, phase angle of entrainment, and phase shifts to 9-h delay of zeitgebers. Mean ± SD.
African American | European American | |
---|---|---|
N | 23 | 22 |
Free-Running Period (τ) (h) | 24.06 ± 0.19 | 24.31 ± 0.24* |
Baseline Circadian Phasea (h:min) | 21:37 ± 2:05 | 22:35 ± 1:53 |
Bedtimeb (h:min) | 23:52 ± 1:08 | 0:27 ± 1:11 |
Waketimeb (h:min) | 7:52 | 8:27 |
Phase Angle of Entrainmentc (h) | −2.3 ± 1.5 | −1.9 ± 1.5 |
Phase Delayd (h) | −2.4 ± 1.3 | −3.6 ± 1.0* |