Sleep and BMI in South African urban and rural, high and low-income preschool children

Rae, Dale E.; Tomaz, Simone A.; Jones, Rachel A.; Hinkley, Trina; Twine, Rhian; Kahn, Kathleen; Norris, Shane A.; Draper, Catherine E.

doi:10.1186/s12889-021-10591-5

BMC Public Health

Table 2 Sleep characteristics of participants stratified by sex and setting group

From: Sleep and BMI in South African urban and rural, high and low-income preschool children

	All (n = 198)	Boys (n = 98)	Girls (n = 100)	P-value	Rural Low (n = 111)	Urban Low (n = 65)	Urban High (n = 22)	P-value
Average
Bedtime (hh:mm)	20:08 (19:32, 21:02)	20:12 (19:38, 21:12)	20:01 (19:22, 21:00)	0.085	19:38 (19:11, 20:08)	21:20 (21:01, 21:41)^c	19:56 (19:35, 20:22)	*< 0.001*
Wake-up time (hh:mm)	06:40 (06:22, 07:09)	06:42 (06:22, 07:18)	06:39 (06:22, 07:00)	0.242	06:26 (06:11, 06:44)	07:11 (06:53, 07:32)^c	06:43 (06:21, 07:19)	*< 0.001*
Nocturnal time-in-bed (h)	10.48 ± 0.77	10.44 ± 0.07	10.52 ± 0.08	0.478	10.76 ± 0.68	9.92 ± 0.68^c	10.76 ± 0.61	*< 0.001*
Nap duration (h)^a	0.97 (0.80, 1.24)	0.86 (0.77, 1.13)	1.07 (0.90, 1.41)	*0.008*	0.94 (0.77, 1.22)	1.03 (0.83, 1.33)	0.89 (0.81, 1.02)	0.367
Week
Bedtime (hh:mm)	20:02 (19:29, 21:01)	20:13 (19:37, 21:11)	19:54 (19:19, 20:53)	*0.049*	19:40 (19:10, 20:06)	21:18 (20:59, 21:41)^c	19:49 (19:29, 20:13)	*< 0.001*
Wake-up time (hh:mm)	06:34 (06:11, 06:59)	06:37 (06:11, 07.11)	06:31 (06:11, 06:52)	0.268	06:17 (06:04, 06:34)	07:04 (06:40, 07:24)^c	06:44 (06:23, 07:05)	*< 0.001*
Nocturnal time-in-bed (h)	10.39 ± 0.80	10.33 ± 0.07	10.45 ± 0.09	0.310	10.63 ± 0.68	9.81 ± 0.70^c	10.90 ± 0.70	*< 0.001*
Nap duration (h)^a	1.00 (0.80, 1.30)	0.86 (0.77, 1.12)	1.11 (0.91, 1.48)	*0.002*	1.01 (0.79, 1.31)	1.03 (0.85, 1.45)	0.83 (0.74, 0.95)	0.182
Weekend
Bedtime (hh:mm)	20:13 (19:30, 21:11)	20:19 (19:33, 21:14)	20:05 (19:26, 21:02)	0.350	20:21 (19:58, 20:49)	21:31 (20:55, 22:03)^c	19:35 (19:13, 20:13)	*< 0.001*
Wake-up time (hh:mm)	06:59 (06:31, 07:32)	07:04 (06:30, 07:39)	06:58 (06:32, 07:23)	0.276	06.37 (06:17, 07:21)	07:41 (07:05, 07:59)^c	06:46 (06:20, 07:10)	*< 0.001*
Nocturnal time-in-bed (h)	10.72 (10.04, 11.41)	10.57 (10.02, 11.44)	10.81 (10.05, 11.37)	0.995	10.32 (10.04, 10.88)^b	10.10 (9.63, 10.58)^c	11.14 (10.52, 11.54)^b	*< 0.001*
Nap duration (h)^a	0.90 ± 0.32	0.83 ± 0.34	0.99 ± 0.30	0.132	0.89 ± 0.30	0.85 ± 0.37	0.95 ± 0.30	0.644

Data are presented as mean ± SD or median with interquartile range
Significance was determined using independent t-tests, Mann Whitney-U, one-way ANOVA or Kruskal-Wallis ANOVA tests
^aSample size for naps: Average: n = 103, weekdays: n = 103 and weekend days: n = 40
^bPost hoc analyses indicate significant differences between two marked groups
^cPost hoc analyses indicate that marked group is significantly different to the other two groups. Significance was accepted at p < 0.05

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ISSN: 1471-2458

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