Table 2. Variation in sleep patterns recorded in sleep logs, questionnaires, and by actigraphy.

		Overall			Weekdays			Weekend
		Sleep log	Questionnaire	Actigraphy	Sleep log	Questionnairea	Actigraphy	Sleep log	Questionnairea	Actigraphy
Bedtime	mean		21:09	21:39			21:32			22:01
	95% CI		21:01–21:18	21:28–21:49			21:21–21:42			21:45–22:16
	P		<0.001			<0.001			<0.001
Sleep onset time	mean	21:31	21:32	21:47	21:25		21:40	21:45		22:08
	95% CI	21:22–21:40	21:23–21:40	21:36–21:58	21:16–21:35		21:29–21:51	21:31–22:00		21:53–22:24
	Pb	<0.001	ns		0.004	ns		<0.001	0.001
	P	<0.001	0.001		<0.001	ns		<0.001	<0.001
Sleep latency	mean		0:22	0:08			0:09			0:08
	95% CI		0:18–0:27	0:07–0:09			0:07–0:10			0:06–0:09
	P		<0.001			<0.001			<0.001
Sleep end time	mean	7:22	7:17	7:13	7:16		7:07	7:29		7:24
	95% CI	7:13–7:30	7:10–7:24	7:05–7:22	7:08–7:25		6:59–7:15	7:16–7:41		7:11–7:37
	P	<0.001	ns		<0.001	<0.001		ns	ns
Sleep period	mean	9:49	9:45	9:26	9:51		9:26	9:38		9:15
	95% CI	9:40–9:56	9:36–9:54	9:18–9:34	9:42–10:00		9:17–9:35	9:25–9:51		9:02–9:29
	P	<0.001	<0.001		<0.001	<0.001		<0.001	<0.001
Night wakings	mean	0.05	0.23	3.47	0.04		3.52	0.09		3.33
	95% CI	0.02–0.09	0.11–0.36	2.90–4.03	0.01–0.07		2.89–4.15	0.01–0.16		2.70–3.96
	P	<0.001	<0.001		<0.001	<0.001		<0.001	<0.001

Times are presented as hh:mm.

^aSleep patterns on the questionnaire for the entire week were also compared with weekday/weekend variables on sleep logs and actigraphy. P-values from paired t-tests are presented without correction in comparisons with actigraphic data in the same column ^bexcept for comparisons with actigraphic bed time.

A P-value less than 0.008 was considered to indicate statistical significance; Bonferroni correction was used to adjust for multiple comparisons for the 6 sleep variables, but not for other parameters.