Table 1

Sleep habits shown as means (hh:mm/day) and standard deviations (SD) among Finnish school-aged children (n = 337–353)†
2006 2008 ∆ 2006–2008
4th and 5th graders 5th and 6th graders
Girls (n = 177–181) † mean SD mean SD mean SD
Bedtime school day 21:29 0:37 21:48 0:37 0:23*** 0:36
Wake-up time school day 7:10 0:26 7:01 0:25 −0:10*** 0:30
Bedtime weekend 22:18 0:48 22:44 0:48 0:26*** 0:47
Wake-up time weekend 8:42 0:53 9:08 0:59 0:27*** 0:52
Discrepancy of bedtimes 0:53 0:35 0:56 0:38 0:04 0:42
Sleep duration school day 9:48 0:40 9:13 0:43 −0:32*** 0:46
Sleep duration weekend 10:24 0:57 10:24 1:00 0:01 1:04
Discrepancy in sleep duration 0:39 0:58 1:12 1:00 0:33*** 1:07
Boys (n = 159–172) †
Bedtime school day 21:24 0:41 21:41 0:39 0:18*** 0:39
Wake-up time school day 7:06 0:30 7:07 0:25 0:00 0:35
Bedtime weekend 22:24 0:50 22:51 0:59 0:27*** 0:48
Wake-up time weekend 8:27 1:08 8:54 1:10 0:27*** 1:01
Discrepancy of bedtimes 1:01 0:41 1:11 0:47 0:09* 0:47
Sleep duration school day 9:42 0:48 9:25 0:44 −0:18*** 0:48
Sleep duration weekend 10:03 1:12 10:03 1:08 0:00 1:15
Discrepancy in sleep duration 0:20 1:13 0:37 1:08 0:18** 1:13
All (n = 337–353) †
Bedtime school day 21:25 0:39 21:48 0:38 0:20*** 0:37
Wake-up time school day 7:08 0:28 7:03‡ 0:25 −0:05** 0:32
Bedtime weekend 22:21 0:49 22:48 0:54 0:26*** 0:47
Wake-up time weekend 8:35‡ 1:01 9:01‡ 1:05 0:27*** 0:57
Discrepancy of bedtimes 0:57 0:38 1:04‡‡ 0:44 0:06* 0:44
Sleep duration school day 9:43 0:44 9:19‡‡ 0:44 −0:25*** 0:47
Sleep duration weekend 10:14‡‡ 1:05 10:14‡‡ 1:05 0:00 1:10
Discrepancy in sleep duration 0:30‡‡ 1:06 0:55‡‡‡ 1:06 0:26*** 1:10

† Range of respondents in the analyses.

Difference between study years *** ≤0.001, **≤0.01 *≤0.05, paired sample t-test.

Difference between gender within years ‡‡‡≤0.001, ‡‡≤0.01, ‡≤0.05, independent-samples t-test.

Nuutinen et al.

Nuutinen et al. BMC Public Health 2013 13:684   doi:10.1186/1471-2458-13-684

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