Effects of an advanced sleep schedule and morning short wavelength light exposure on circadian phase in young adults with late sleep schedules

Katherine M. Sharkey, Mary A. Carskadon, Mariana G. Figueiro, Yong Zhu, Mark S. Rea

Research output: Contribution to journalArticlepeer-review

60 Scopus citations

Abstract

Objective: We examined the effects of an advanced sleep/wake schedule and morning short wavelength (blue) light in 25 adults (mean age ± SD=21.8 ± 3. years; 13 women) with late sleep schedules and subclinical features of delayed sleep phase disorder (DSPD). Methods: After a baseline week, participants kept individualized, fixed, advanced 7.5-h sleep schedules for 6. days. Participants were randomly assigned to groups to receive " blue" (470. nm, ~225. lux, n=12) or " dim" (<1. lux, n=13) light for 1. h after waking each day. Head-worn " Daysimeters" measured light exposure; actigraphs and sleep diaries confirmed schedule compliance. Salivary dim light melatonin onset (DLMO), self-reported sleep, and mood were examined with 2 × 2 ANOVA. Results: After 6. days, both groups showed significant circadian phase advances, but morning blue light was not associated with larger phase shifts than dim-light exposure. The average DLMO advances (mean ± SD) were 1.5 ± 1.1. h in the dim light group and 1.4 ± 0.7. h in the blue light group. Conclusions: Adherence to a fixed advanced sleep/wake schedule resulted in significant circadian phase shifts in young adults with subclinical DSPD with or without morning blue light exposure. Light/dark exposures associated with fixed early sleep schedules are sufficient to advance circadian phase in young adults.

Original languageEnglish
Pages (from-to)685-692
Number of pages8
JournalSleep Medicine
Volume12
Issue number7
DOIs
StatePublished - Aug 2011
Externally publishedYes

Keywords

  • Blue light
  • Circadian rhythm sleep disorders
  • Circadian rhythms
  • Delayed sleep phase syndrome
  • Human
  • Phase shift
  • Sleep

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