Table 1.

Demographic and sleep-related characteristics of participants

	Longer sleep duration (n = 79)	Shorter sleep duration (n = 74)	t	p
Demographic characteristics
Age (years)	37.6 ± 11.9	37.6 ± 12.0	−0.03	0.97
Sex (No. of male/female)	31/48	45/29		0.01*
Education (years)	15.5 ± 2.5	16.0± 2.0	−1.25	0.21
Actigraphy measures
Total sleep time (min)	423.13± 53.7	295.0± 54.5	14.7	<0.001
Sleep efficiency (%)	88.5 ± 4.7	83.0 ± 7.4	5.55	<0.001
Wake time after sleep onset (min)	48.6 ± 25.5	53.9 ± 29.1	−1.19	0.23
Self-reported sleep measures
PSQI, total (score)	6.1 ± 2.1	7.1 ± 2.2	−3.04	0.003
PSQI, habitual sleep duration (min)	393.5 ± 66.2	360.5 ± 61.2	3.21	0.002

Data are presented as mean ± standard deviation unless specified otherwise. Based on actigraphy-measured sleep duration acquired the night before the MRI scan, participants were divided into the following two groups: 1) shorter sleep duration (< 6 hours) and 2) longer sleep duration (≥ 6 hours).

^*p value from the chi-square test

PSQI, Pittsburgh sleep quality index.