Clinical and polysomnographic characteristics of REM-related obstructive sleep apnea patients

Introduction The clinical importance of obstructive sleep apnea (OPSA), which can be prevalent during rapid eye movement (REM) sleep, is unclear. This study aimed to explore possible differences between patients with REM-related OSA and non-REM-related OSA. Methods This retrospective study consisted of two groups of OSA patients, matched in age, gender and body mass index, who were examined at a Greek tertiary hospital; 147 patients with REM-related OSA were compared with 147 patients with non-REM-related OSA. Results Respiratory events occurred predominantly during REM sleep in REM-related OSA patients (p<0.001) and during non-rapid eye movement sleep (NREM) in the control group (p<0.001). The majority of REM-related OSA patients had mild OSA, while the majority of the control group had severe OSA. REM-related OSA patients had lower Arousal Index (p<0.001), lower Oxygen Desaturation Index (p<0.001), lower percent of recording time, spent at oxyhemoglobin saturation below 90% (p<0.001) and shorter mean event duration (p<0.001). The average SatO 2 % and the minimum SatO 2 % oxyhemoglobin saturation during sleep, were significantly higher, compared to the control group (p=0.002 and p=0.005, respectively). When comparing the anthropometric characteristics, the majority of the clinical features and the reported comorbidities, no significant differences were found between the two groups. However, REM-related OSA patients reported less frequently, excessive daytime sleepiness (p<0.001). Also, a positive correlation was found between reported insomnia and the minimum SatO 2 % in them. Conclusions Our results show that REM-related OSA patients, despite their milder polysomnographic phenotype, they do not carry a lighter comorbidity load, when compared to non-REM-related OSA patients.