Table 2.

Age-adjusted difference between subset of morning and evening types. Due to the significant difference in age between the morning and evening types in our sample, we included age in our statistical model when determining whether there were differences between the two chronotypes. The difference between evening and morning types (mean ± standard error) and the associated P value are presented. We calculated the mean value for each group by adjusting both groups to age 35 years, which was the average age of the neither type group of participants

	M versus E difference	P value	M mean (age-adjusted)	E mean (age-adjusted)
Weekday bed time	2:32 ± 0:22	0.0001	22:33	1:05
Weekday wake time	2:24 ± 0:23	0.0001	6:17	8:40
Weekend bed time	2:22 ± 0:21	0.0001	23:09	1:32
Weekend wake time	3:14 ± 0:23	0.0001	7:18	10:31
Weekend bed time delay	−0:10 ± 0:12	0.4	0:36	0:26
Weekend wake time delay	0:50 ± 0:26	0.061	1:01	1:51
Weekday sleep duration (h)	−0.14 ± 0.36	0.7	7.73	7.58
Weekend sleep duration (h)	0.86 ± 0.34	0.015	8.13	8.99
Weekend sleep extension (h)	1.0 ± 0.45	0.031	0.41	1.41
Perceived sleep need (h)	0.29 ± 0.26	0.3	7.85	8.14
PSQI score	−0.04 ± 0.51	0.4	3.72	3.68
ESS score	−1.16 ± 0.92	0.2	7.74	6.58

Abbreviations: ESS, Epworth Sleepiness score; PSQI, Pittsburgh Sleep Quality index; M, morning; E, evening; h, hour.