Table 1.
Summary of demographic data, sleep and physiological variables for early (ECT) and late (LCT) chronotypes
| Variable measured (mean ± SEM) | ECTs | LCTs | Significance |
|---|---|---|---|
| Sample size | N = 25 | N = 31 | n/a |
| Number of testing sessions | N = 75 | N = 93 | n/a |
| Number of males/females | M = 9 | M = 14 | p = 0.59 (ns)b |
| F = 16 | F = 17 | ||
| Age (years) (mean ± SD) | 22.8 ± 4.5 | 20.8 ± 3.0 | p = 0.084 (ns)a |
| Height (cm) | 172.5 ± 1.7 | 172.5 ± 1.9 | p = 0.99 (ns)a |
| Weight (kg) | 67.7 ± 2.3 | 69.8 ± 2.0 | p = 0.55 (ns)a |
| MSFsc (hh:mm) | 02:38 ± 00:07 | 06:59 ± 00:12 | p < 0.0001a |
| Sleep onset (hh:mm) | 23:03 ± 00:07 | 02:36 ± 00:14 | p < 0.0001a |
| Wake-up time (hh:mm) | 06:45 ± 00:08 | 10:30 ± 00:14 | p < 0.0001a |
| Sleep duration (h) | 7.69 ± 0.14 | 7.85 ± 0.14 | p = 0.55 (ns)a |
| Dim light melatonin onset (hh:mm) | 20:27 ± 00:16 | 23:55 ± 00:26 | p < 0.0001a |
| Cortisol peak time (hh:mm) | 07:04 ± 00:16 | 11:13 ± 00:23 | p < 0.0001a |
Values are shown as mean ± SEM unless specified. The significance is shown with aunpaired two-sample t tests, bFisher’s exact test. MSFsc = corrected mid-sleep time of free days. All p values are corrected for the false discovery rate