title: Delayed sleep onset in depressed young people.
abstract: BACKGROUND
  The circadian abnormality of delayed sleep phase has been suggested to characterise a subgroup of depressed young adults with different risk factors and course of illness. We aim to assess the prevalence and factors, particularly substance use, associated with such delay in a large help-seeking cohort of young people with mental health problems.
  
  
  METHODS
  From a consecutively recruited sample of 802 help-seeking young people, 305 (38%) had at least moderate depressive symptoms (QIDS-C16 >10), sleep data and did not have a chronic severe mental illness. Demographic and clinical characteristics were evaluated through self report and clinical interview. Delayed sleep phase was defined as a sleep onset between the hours of 02:00 a.m. - 06:00 a.m. and the characteristics of this group were compared to normal phase sleepers.
  
  
  RESULTS
  Delayed sleep onset was reported amongst 18% (n = 56/305) of the depressed group compared to 11% of the non-depressed young people. Amongst the depressed group, delayed sleep onset was associated with tobacco, alcohol and cannabis misuse and short sleep duration (x̅: 5.8 hrs vs. x̅: 7.8 hrs). There were no differences in demographic factors, personality traits or symptoms. Tobacco smoking was very common: In logistic regression analyses only tobacco use (OR 2.28, 95% CI: 1.04 - 5.01) was associated with delayed sleep onset. There was no interaction with age.
  
  
  CONCLUSIONS
  Delayed sleep onset was twice as common in depressed young people as the general population and young people with other mental health problems, and is a potential marker for a subgroup of mood disorders. Those with delayed sleep onset were not more severely depressed but had short sleep duration, a risk for chronic psychological ill health, and higher levels of tobacco use. Nicotine use was common in this group, has biological evidence as a sleep disrupter, and requires specifically addressing in this population.
authors: Brain and Mind Research Institute, University of Sydney, Sydney, New South Wales, Australia. nick.glozier@sydney.edu.au.
authors: Nicholas
authors: N
authors: Glozier
authors: Bridianne
authors: B
authors: O'Dea
authors: Patrick D
authors: PD
authors: McGorry
authors: Christos
authors: C
authors: Pantelis
authors: Günter Paul
authors: GP
authors: Amminger
authors: Daniel F
authors: DF
authors: Hermens
authors: Rosemary
authors: R
authors: Purcell
authors: Elizabeth
authors: E
authors: Scott
authors: Ian B
authors: IB
authors: Hickie
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002940:Circadian Rhythm / Q000502:physiology*; D003863:Depression / Q000150:complications* / Q000503:physiopathology; D003866:Depressive Disorder / Q000150:complications* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D011569:Psychiatric Status Rating Scales; D012307:Risk Factors; D057566:Self Report; D012890:Sleep / Q000502:physiology*; D012893:Sleep Wake Disorders / Q000150:complications* / Q000503:physiopathology; D012917:Social Adjustment; D055815:Young Adult