Table I. Descriptive statistics.

Descriptive statistics of actigraphic measures throughout the daily intervals. Lights-off is from 1800h-0600h. Lights-on is from 0600h–1800h. The morning and evening lights-on periods are from 0600h–1200h and 1200h–1800h, respectively. The stability measure was calculated as one minus the coefficient of variation calculated on all measures within each individual subject. Asterisks indicate measures for which significant group differences were found.

	Interval	Data Type	Mean	Min.	Max.	Std. Dev	CV %	Stability
Mother-reared	Daily	Activity Count *	85.42	71.08	100.57	10.55	0.12	0.88
	Lights-on	Sleep time (min) *	226.34	165.88	301.00	49.96	0.22	0.78
	Daily	Sleep time (min)	929.94	853.22	1101.50	88.06	0.09	0.91
	Evening lights-on	Sleep time (min)	144.75	104.78	213.91	38.06	0.26	0.74
	Morning lights-on	Sleep time (min) *	82.72	50.31	124.09	25.77	0.31	0.69
	Lights-off	Sleep time (min)	684.18	656.72	700.66	15.17	0.02	0.98
	Sleep	Sleep time (min) *	608.98	530.72	671.31	49.39	0.08	0.92
	Sleep	Sleep efficiency	97.50	95.32	99.16	1.42	0.01	0.99
	Sleep	Early Wake (min) *	64.38	8.34	127.31	41.08	0.64	0.36
Nursery-reared	Daily	Activity Count *	85.98	69.58	98.57	10.65	0.12	0.88
	Lights-on	Sleep time (min) *	277.08	218.06	356.84	48.43	0.17	0.83
	Daily	Sleep time (min)	960.10	895.72	1047.75	53.56	0.06	0.94
	Evening lights-on	Sleep time (min)	154.04	115.44	186.19	25.15	0.16	0.84
	Morning lights-on	Sleep time (min) *	123.05	85.44	179.56	34.24	0.28	0.72
	Lights-off	Sleep time (min)	677.94	661.84	693.53	10.28	0.02	0.98
	Sleep	Sleep time (min) *	580.13	510.78	639.13	46.44	0.08	0.92
	Sleep	Sleep efficiency	97.30	95.66	98.53	0.94	0.01	0.99
	Sleep	Early Wake (min) *	85.51	30.31	157.78	44.35	0.52	0.48