Protective effects of REM sleep without atonia against obstructive sleep apnea in patients with idiopathic REM sleep behavior disorder.

BACKGROUND: This study investigated the protective effect of rapid eye movement (REM) sleep without atonia against obstructive sleep apnea (OSA) in patients with idiopathic REM sleep behavior disorder (RBD).

METHODS: In this case-control study, patients with idiopathic RBD and OSA (RBD-OSA) were consecutively enrolled and OSA controls without RBD were matched for age, sex, and apnea-hypopnea index (AHI). Clinical and polysomnographic characteristics were compared between RBD-OSA patients and OSA controls. Additionally, differences in AHIs depending on sleep state and posture were analyzed.

RESULTS: In total, 109 OSA patients (81 males and 28 females) with idiopathic RBD were included in the study. In OSA controls without RBD, AHI and respiratory distress index (RDI) were significantly higher during REM sleep than during non-rapid eye movement (NREM) sleep (p < 0.01). In RBD-OSA patients, however, AHI and RDI were slightly lower during REM sleep than during NREM sleep (p < 0.05). During REM sleep, AHI and RDI were significantly lower in RBD-OSA patients than in OSA controls (p < 0.001). Differences in apnea severity between RBD-OSA patients and OSA controls increased in supine REM sleep but disappeared or lessened in non-supine REM sleep. The prevalence of REM-related OSA was lower in RBD-OSA patients (9.2%) than in OSA controls (33.0%).

CONCLUSIONS: REM sleep without atonia has protective effects against OSA in patients with idiopathic RBD. These protective effects are much more potent in supine sleep than in non-supine sleep.