Objective: The existence of a rapid eye movement (REM)-specific sleep-disordered breathing (SDB) has been suggested based on the finding of an association between sleepiness and respiratory disturbances confined primarily to REM sleep. The aim of the study was to define the frequency and the clinical and polysomnographic features of REM SDB in a large clinical population.
Methods: Anthropometric, clinical, and polysomnographic characteristics of 415 patients undergoing polysomnography for SDB were examined. For all patients the apnea-hypopnea index (AHI) during total sleep time, the AHI during REM (AHI-REM), and the AHI during non-REM sleep (AHI-NREM) were calculated. REM SDB was defined as an AHI-REM/AHI-NREM ratio >2. Patients were stratified according to the severity of disease in mild, moderate, and severe cases. Daytime sleepiness was assessed subjectively by the Epworth sleepiness scale (ESS), and objectively, in a subgroup of 228 patients, by the maintenance wakefulness test (MWT).
Results: Of the initial sample, 36.4% of cases (n = 151) fulfilled the REM SDB criteria. No significant differences in subjective complaints, medical history, and drug intake were present between REM and non-REM SDB patients, and no significant differences were found in ESS scores and mean sleep latency of the MWT between groups. A high occurrence of REM SDB was found in mild (73.1%) and moderate cases (47.2%). While in the entire group and in non-REM SDB patients a strong male prevalence was found, the incidence of REM SDB was similar in men and women.
Conclusion: Our results show that neither clinical history nor daytime sleepiness differentiate patients with REM SDB from non-REM SDB patients. The disorder is more common in mild and moderate cases; there is an equal incidence in women and men. These findings may suggest that REM-related SDB is a part of the spectrum of SDB.