title: The effects of sleep and light at night on melatonin in adolescents.
abstract: OBJECTIVE
  The circadian hormone melatonin has wide-reaching effects on human physiology. In adolescents, the impact of nighttime light exposure and other modifiable behavioral factors on melatonin levels is poorly understood.
  
  
  METHODS
  We cross-sectionally examined the influence of nighttime behaviors on melatonin levels in 100 adolescents (average age: 15.7; 55 female, 45 male), who completed a self-administered questionnaire and provided a first morning urine sample to assay for urinary 6-sulfatoxymelatonin (aMT6s) levels. We used mixed-effects regression models to test for differences in aMT6s levels by categories of covariates.
  
  
  RESULTS
  Self-reported sleep duration, ambient light levels during sleep, and use of electronics after turning off lights did not significantly predict aMT6s levels. Compared to those who reported weekend bedtimes before 11 pm, urinary aMT6s levels were significantly lower among participants reporting weekend bedtimes after midnight (52.5 vs. 38.0 ng/mg creatinine, P trend=0.007). Sleep interruption also appeared to be significantly associated with lower urinary aMT6s levels, but only if lights were turned on during sleep interruption (43.0 ng/mg creatinine for participants with sleep interruption but not turning lights on, vs. 24.6 ng/mg creatinine for participants reporting that they turned on the light when their sleep was interrupted P difference=0.032).
  
  
  CONCLUSIONS
  Our study suggests that self-reported sleep-related behaviors have little to no effect on adolescent circadian systems, though larger studies are needed to confirm our findings.
authors.affiliation: The College of Brown University, Brown University, Providence, RI, USA.
authors.forename: Caleb
authors.initials: C
authors.lastname: Hersh
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Julia
authors.initials: J
authors.lastname: Sisti
authors.affiliation: UC Health University Hospital Clinical Laboratories, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
authors.forename: Vincent
authors.initials: V
authors.lastname: Richiutti
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA, Applied Cancer Research - Institution for Translational Research Vienna (ACR-ITR VIEnna), Vienna, Austria.
authors.forename: Eva
authors.initials: E
authors.lastname: Schernhammer
mesh_terms: D000293:Adolescent; D041923:Adolescent Development / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D012890:Sleep / Q000502:physiology*
chemical_list: D008550:Melatonin