Table 1.

Descriptive statistics for study variables (N = 119)

Variable	%	n	Mean	SD	Range
Age of adolescent			19.01	0.42	17.93 – 20.10
ake time (self-report) hh:mm			08:38	1:28	03:13 – 13:30
Wake time (Actigraph) hh:mm			08:47	1:22	05:48 – 12:33
Hours of nighttime sleep (self-report)			7.71	1.34	3.00 – 10.61
Hours of nighttime sleep (Actigraph)			6.41	1.07	1.41 – 9.55
Sleep efficiency % (Actigraph)			81.85	7.61	48.80 – 92.60
Hours of naptime (self-report)			0.41	0.77	0.00 – 04.72
Average waketime cortisol (μg/dl)			0.30	0.21	0.01 – 1.37
Average +30 min cortisol (μg/dl)			0.50	0.25	0.01 – 1.78
Average + 3 hours cortisol (μg/dl)			0.28	0.20	0.03 – 1.80
Average + 8 hours cortisol (μg/dl)			0.16	0.11	0.03 – 0.82
Average + 12 hours cortisol (μg/dl)			0.12	0.11	0.01 – 0.76
Average bedtime cortisol (μg/dl)			0.10	0.11	0.01 – 0.71
Caffeine (drinks per day)			0.91	1.40	0.00 – 8.00
Nicotine (cigarettes per day)			0.28	0.82	0.00 – 5.00
Alcohol (drinks per week)			4.38	7.45	0.00 – 50.00
Exercise (hours per week)			2.77	4.07	0.00 – 30.00
Oral contraceptive use (females only)	35.5	33
Asthma medication	7.6	9
Depression medication	4.2	5
Male	21.8	26
European American	61.4	73
African American	17.6	21
Hispanic	4.2	5
Multiple/other race	16.8	20