title: Longitudinal course and risk factors for fatigue in adolescents: the mediating role of sleep disturbances.
abstract: OBJECTIVE
  This study (1) examines fatigue over 1 year in adolescents with chronic pain (n = 61) and depressive disorders (n = 51) compared with healthy adolescents (n = 60), (2) identifies longitudinal risk factors, and (3) tests sleep disturbances as a mediator between depression and fatigue.
  
  
  METHODS
  Adolescents completed questionnaires at baseline, 6, and 12 months. Mixed effects models examined associations between risk factors and fatigue; structural equation modeling assessed contemporaneous and longitudinal mediation.
  
  
  RESULTS
  Results revealed fatigue persisted at 1 year follow-up, with adolescents in the clinical samples experiencing greater fatigue than healthy youth at all time points (ps < .001). Age, baseline depression, and baseline sleep disturbances predicted longitudinal fatigue for the total sample (ps < .05), with variation in predictors by subgroup. Sleep quality mediated the contemporaneous effects of depression on fatigue in the clinical samples (ps < .05).
  
  
  CONCLUSIONS
  Findings underscore the longitudinal course of fatigue and suggest that improving sleep disturbances may reduce fatigue in clinical samples.
authors.affiliation: M.B.B.S, Senior Fellow & Acting Instructor, Dept. of Anesthesiology & Pain Medicine, Seattle Children's Hospital, 4800 Sand Point Way, Seattle, WA 98105, USA. see.tham@seattlechildrens.org.
authors.forename: See Wan
authors.initials: SW
authors.lastname: Tham
authors.forename: Amy Lewandowski
authors.initials: AL
authors.lastname: Holley
authors.forename: Chuan
authors.initials: C
authors.lastname: Zhou
authors.forename: Gregory N
authors.initials: GN
authors.lastname: Clarke
authors.forename: Tonya M
authors.initials: TM
authors.lastname: Palermo
mesh_terms: D000293:Adolescent; D000367:Age Factors; D059350:Chronic Pain / Q000453:epidemiology / Q000503:physiopathology*; D015897:Comorbidity; D003866:Depressive Disorder / Q000453:epidemiology / Q000503:physiopathology*; D005221:Fatigue / Q000453:epidemiology / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D012893:Sleep Wake Disorders / Q000453:epidemiology / Q000503:physiopathology*; D013995:Time
keywords: adolescents; depression; fatigue; recurrent and chronic pain; sleep