Prevalence and correlates of delayed sleep phase in high school students

Saxvig, Ingvild W.; Pallesen, Ståle; Wilhelmsen-Langeland, Ane; Molde, Helge; Bjorvatn, Bjørn

doi:10.1016/j.sleep.2011.10.024

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Volume 13, Issue 2 , Pages 193-199, February 2012

Prevalence and correlates of delayed sleep phase in high school students

Ingvild W. Saxvig
- Department of Public Health and Primary Health Care, University of Bergen, Postboks 7804, 5020 Bergen, Norway
- Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Jonas Lies vei 65, 5021 Bergen, Norway
- Corresponding author at: Department of Public Health and Primary Health Care, University of Bergen, Postboks 7804, 5020 Bergen, Norway. Tel.: +47 55586064; fax: +47 55586130.
Ståle Pallesen
- Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Jonas Lies vei 65, 5021 Bergen, Norway
- Department of Psychosocial Science, University of Bergen, Postboks 7807, 5020 Bergen, Norway
Ane Wilhelmsen-Langeland
- Department of Public Health and Primary Health Care, University of Bergen, Postboks 7804, 5020 Bergen, Norway
Helge Molde
- Department of Psychosocial Science, University of Bergen, Postboks 7807, 5020 Bergen, Norway
Bjørn Bjorvatn
- Department of Public Health and Primary Health Care, University of Bergen, Postboks 7804, 5020 Bergen, Norway
- Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Jonas Lies vei 65, 5021 Bergen, Norway

Received 7 April 2011; received in revised form 12 September 2011; accepted 2 October 2011.

Abstract

Purpose

To investigate prevalence and correlates of delayed sleep phase, characterized by problems falling asleep in the evening and rising at adequate times in the morning, in a large sample of Norwegian high school students.

Methods

A randomized sample of 1285 high school students (aged 16–19years) participated in an internet based study answering questions about sleep habits, height, weight, smoking, alcohol use, school grades, and anxiety and depression symptoms. Delayed sleep phase was operationalized as difficulties falling asleep before 2a.m. at least three nights per week together with much or very much difficulty waking up in the morning.

Results

The results show a prevalence of delayed sleep phase of 8.4%. In all, 68% of these students (5.7% of the total sample) also reported problems advancing their sleep period as well as one daytime consequence (oversleeping at least two days a week or experiencing much/very much sleepiness at school). Delayed sleep phase was associated with lower average school grades, smoking, alcohol usage, and elevated anxiety and depression scores.

Conclusions

Delayed sleep phase appears to be common amongst Norwegian adolescents and is associated with negative outcomes such as lower average school grades, smoking, alcohol usage, and elevated anxiety and depression scores.

Keywords: Sleep, Sleep patterns, Circadian rhythm, Adolescents, Prevalence, Delayed sleep phase syndrome