title: Ambient temperature and obstructive sleep apnea: effects on sleep, sleep apnea, and morning alertness.
abstract: OBJECTIVE
  The aim of the study was to investigate the effect of ambient temperature on sleep, sleep apnea, and morning alertness in patients with obstructive sleep apnea.
  
  
  METHODS
  Randomized controlled trial.
  
  
  METHODS
  In-hospital investigations.
  
  
  METHODS
  Forty patients with obstructive sleep apnea naïve to treatment, with an apnea-hypopnea index of 10-30.
  
  
  METHODS
  Three different nights in room temperatures of 16°C, 20°C, and 24°C.
  
  
  METHODS
  Overnight polysomnography and Karolinska Sleepiness Scale.
  
  
  RESULTS
  The obstructive apnea-hypopnea index was 30 ± 17 at 16°C room temperature, 28 ± 17 at 20°C, and 24 ± 18 at 24°C. The obstructive apnea-hypopnea index was higher at 16°C room temperature versus 24°C (P = 0.001) and at 20°C room temperature versus 24°C (P = 0.033). Total sleep time was a mean of 30 min longer (P = 0.009), mean sleep efficiency was higher (77 ± 11% versus 71 ± 13% respectively, P = 0.012), and the patients were significantly more alert according to the Karolinska Sleepiness Scale (P < 0.028) in the morning at 16°C room temperature versus 24°C. The amount of sleep in different sleep stages was not affected by room temperature.
  
  
  CONCLUSIONS
  Untreated patients with obstructive sleep apnea sleep longer, have better sleep efficiency, and are more alert in the morning after a night's sleep at 16°C room temperature compared with 24°C, but obstructive sleep apnea is more severe at 16°C and 20°C compared with 24°C.
  
  
  BACKGROUND
  This study is registered in ClinicalTrials.gov number NCT00544752.
authors.affiliation: Department of Internal Medicine, Umeå University, Umeå, Sweden. Fredrik.Valham@Lung.Umu.Se
authors.forename: Fredrik
authors.initials: F
authors.lastname: Valham
authors.forename: Carin
authors.initials: C
authors.lastname: Sahlin
authors.forename: Hans
authors.initials: H
authors.lastname: Stenlund
authors.forename: Karl A
authors.initials: KA
authors.lastname: Franklin
mesh_terms: D000368:Aged; D001143:Arousal / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology* / Q000523:psychology / Q000628:therapy*; D012894:Sleep Stages / Q000502:physiology*; D013696:Temperature; D013997:Time Factors; D016896:Treatment Outcome