title: The contribution of fatigue and sleepiness to depression in patients attending the sleep laboratory for evaluation of obstructive sleep apnea.
abstract: OBJECTIVE
  A high prevalence of depressive symptomatology has been reported amongst sufferers of obstructive sleep apnea (OSA), but it remains unclear as to whether this is due to their OSA or other factors associated with the disorder. The current study aimed to assess the incidence and aetiology of depression in a community sample of individuals presenting to the sleep laboratory for diagnostic assessment of OSA.
  
  
  METHODS
  Forty-five consecutive individuals who presented to the sleep laboratory were recruited; of those, 34 were diagnosed with OSA, and 11 were primary snorers with no clinical or laboratory features of OSA. Nineteen control subjects were also recruited. Patients and controls completed the Beck Depression Inventory, the Profile of Mood States (POMS), and the Epworth Sleepiness Scale to assess their mood and sleepiness, prior to their polysomnography.
  
  
  RESULTS
  All patients reported significantly more depressive symptoms compared with healthy controls, regardless of their degree of OSA. There were no significant differences between OSA patients and primary snorers on any of the mood and self-rated sleepiness measures. Depression scores were not significantly associated with any of the nocturnal variables. Regression analysis revealed that the POMS fatigue subscale explained the majority of the variance in subjects' depression scores.
  
  
  CONCLUSIONS
  Fatigue was the primary predictor of the level of depressive symptoms in patients who attended the sleep laboratory, regardless of the level of severity of sleep-disordered breathing. When considering treatment options, practitioners should be aware of the concomitant occurrence of depressive symptoms and fatigue in patients presenting with sleep complaints, which may not be due to a sleep disorder.
authors.affiliation: Sleep and Performance Research Center, Washington State University, Spokane, WA 99210, USA. jacksonm@wsu.edu
authors.forename: Melinda L
authors.initials: ML
authors.lastname: Jackson
authors.forename: Con
authors.initials: C
authors.lastname: Stough
authors.forename: Mark E
authors.initials: ME
authors.lastname: Howard
authors.forename: Jo
authors.initials: J
authors.lastname: Spong
authors.forename: Luke A
authors.initials: LA
authors.lastname: Downey
authors.forename: Bruce
authors.initials: B
authors.lastname: Thompson
mesh_terms: D000328:Adult; D000368:Aged; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D006970:Disorders of Excessive Somnolence / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D005221:Fatigue / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D012913:Snoring / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D014739:Victoria; D055815:Young Adult
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