How do short sleepers use extra waking hours? A compositional analysis of 24-h time-use patterns among children and adolescents

Table 1 Characteristics of the study sample

	Total n = 659		Children n = 343		Adolescents n = 316		p-value^c
	Mean^a	var^b	Mean^a	var^b	Mean^a	var^b	p-value^c
Age (years)	13.9	2.8	11.7	1.6	16.3	1.3	< 0.001
Height (cm)	160.5	14.1	151.6	12.0	170.2	8.7	< 0.001
Weight (kg)	52.9	15.0	43.7	11.4	63.0	11.6	< 0.001
BMI^d z-score	0.2	1.1	0.2	1.1	0.2	1.0	0.559
Weight status (% of n)^e
Underweight	1.4		2.0		0.6
‘Normal’ weight	76.1		73.2		79.4
Overweight	17.0		17.2		16.8
Obese	5.5		7.6		3.2
Sleep
% of short sleepers (% of n)	73.3		71.4		75.3
Sleep duration (min/day)^f	490.2	33.1	520.4	32.3	453.7	37.0	< 0.001
Sleep efficiency (%)^g	86.5	4.7	85.6	4.5	87.5	4.7	< 0.001
Waking behaviors^f
SB^h (min/day)	675.6	54.0	623.8	53.6	735.1	47.0	< 0.001
LPAⁱ (min/day)	229.0	33.8	241.2	36.2	215.4	34.9	0.001
MVPA^j (min/day)	45.2	79.0	54.7	77.9	35.6	81.1	0.021

^a Geometric mean for time-use components; arithmetic mean for non-compositional continuous variables; percentages for categorical variables
^b The part of total variance related to a given time-use component; standard deviation for other variables
^c p-value from the t-test for independent samples, where the first pivot coordinate was used to represent each time-use variable
^d Body mass index
^e Categories according to body mass index z-score
^f The respective time-use composition was adjusted to 24 h before the analysis
^g Calculated as the percentage of time spent in sustained inactivity periods divided by the sleep duration
^h Sedentary behavior
ⁱ Light physical activity
^j Moderate-to-vigorous physical activity

ISSN: 1479-5868