Table III. T-tests of activity during the sleep period.

Group statistics of various sleep related indices from the actigraphic analysis are shown in Table III. . The sleep period is the time between sleep onset to sleep end (i.e., wake onset). Total sleep is the time spent sleeping, excluding periods of waking, within the sleep period. The early-wake index is the elapsed time between sleep end to lights-on in the morning. Onset latency is the time between lights-off and sleep onset at night. Sleep efficiency is the percentage of time sleeping (‘total sleep’) divided by the sleep period length. Sleep bouts/h is the frequency of sleeping within the sleep period with a sleep bout defined as one or more consecutive epochs scored as asleep. NS indicates a nonsignificant (p>0.05) two-sample t-test.

	Mother-reared	Nursery-reared	T-value	df	p-value
Sleep Period Length (min)	624.86	596.48	2.81	14	< 0.05
Total Sleep (min)	608.98	580.13	3.44	14	< 0.01
Early-Wake Index (min)	64.38	85.51	−4.27	14	< 0.01
Onset Latency (min)	30.8	38.0	−0.84	14	NS
Sleep efficiency (%)	97.50	97.26	0.32	14	NS
Sleep bouts/h	3.03	2.97	0.12	14	NS