The short and long of adolescent sleep: the unique impact of day length

Kate Bartel, Annette van Maanen, Jamie Cassoff, Oddgeir Friborg, Anne Marie Meijer, Frans Oort, Paul Williamson, Reut Gruber, Barbel Knauper, Michael Gradisar

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Study objectives Variation in day length is proposed to impact sleep, yet it is unknown whether this is above the influence of behavioural factors. Day length, sleep hygiene, and parent-set bedtime were simultaneously explored, to investigate the relative importance of each on adolescents’ sleep. Methods An online survey was distributed in four countries at varying latitudes/longitudes (Australia, The Netherlands, Canada, Norway). Results Overall, 711 (242 male; age M = 15.7 ± 1.6, range = 12–19 yrs) adolescents contributed data. Hierarchical regression analyses showed good sleep hygiene was associated with earlier bedtime, shorter sleep latency, and longer sleep (β = −0.34; −0.30; 0.32, p < 0.05, respectively). Shorter day length predicted later bedtime (β = 0.11, p = 0.009), decreased sleep latency (β = −0.21, p < 0.001), and total sleep (β = −0.14, p = 0.001). Longer day length predicted earlier bedtimes (β = −0.11, p = 0.004), and longer sleep (β = 0.10, p = 0.011). Conclusions Sleep hygiene had the most clinical relevance for improving sleep, thus should be considered when implementing adolescent sleep interventions, particularly as small negative effects of shorter day length may be minimised through sleep hygiene techniques.

Original languageEnglish
Pages (from-to)31-36
Number of pages6
JournalSleep Medicine
Publication statusPublished - Oct 2017


  • Adolescent
  • Day length
  • Parent-set bedtime
  • Sleep
  • Sleep hygiene


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