Study objectives: 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.
Design: Randomized controlled trial.
Setting: In-hospital investigations.
Participants: Forty patients with obstructive sleep apnea naïve to treatment, with an apnea-hypopnea index of 10-30.
Interventions: Three different nights in room temperatures of 16°C, 20°C, and 24°C.
Measurements: 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.
Clinical trial information: This study is registered in ClinicalTrials.gov number NCT00544752.
Keywords: Sleep apnea syndromes; ambient temperature; daytime sleepiness; polysomnography; randomized controlled trial; sleep quality; sleep stages; sleep time; treatment.