Abstract
Objectives
Sleep duration and physical activity decline with age during adolescence. Earlier
school schedules may contribute to these declines. The aim of this longitudinal study
was to track changes in sleep and activity of Icelandic youth from primary to secondary
school and compare students who enrolled in secondary schools with traditional and
college-style schedules.
Methods
We measured free-living sleep and activity with wrist actigraphy and body composition
by dual-energy x-ray absorptiometry in 145 students at age 15 and age 17, when 58%
attended schools with college-style scheduling. Differences from 15 to 17 and between
students of different school structures were assessed with mixed-effect models.
Results
Actigraphs were worn for 7.1 ± 0.4 nights at 15 and 6.9 ± 0.4 nights at 17. Overall,
sleep duration decreased from 6.6 ± 0.7 h/night to 6.2 ± 0.7 h/night from age 15 to
17 (P < .001). Students with traditional schedules reduced school-night sleep duration
26 min/night at follow-up (P< .001), while sleep duration did not change for college-style students. All students
went to bed later on school nights at follow-up, but only college-style students rose
later. Sleep efficiency and awakenings did not differ by schedule-type. Neither sex
changed body fat percentage, but average school-day activity decreased by 19% (P< .001) on follow-up and did not differ by schedule-type.
Conclusions
Over the 2-year period, adolescents decreased weekly sleep duration and activity,
but only those continuing traditional schedules reduced school-night sleep. This suggests
greater individual control of school schedule may preserve sleep duration in this
age group, which may be beneficial during the transition into adulthood.
Keywords
Abbreviations:
BMI (body mass index), WASO (Wake after sleep onset)To read this article in full you will need to make a payment
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Article info
Publication history
Published online: June 11, 2020
Footnotes
The study was performed at the University of Iceland in Reykjavik, Iceland.
Identification
Copyright
Published by Elsevier Inc. on behalf of National Sleep Foundation.
