Nocturnal Sleep Onset Rapid Eye Movement Sleep Periods as a Predictor of the Severity of Narcolepsy in Korea

Abstract

Background and Objective To investigate the severity of narcolepsy based on the presence of nocturnal sleep onset rapid eye movement sleep period (nSOREMP). Methods Subjects included 167 narcolepsy patients diagnosed at the St. Vincent Hospital, the Catholic University of Korea. They underwent polysomnography (PSG) and Multiple Sleep Latency Test (MSLT). The standardized face to face interview and Epworth Sleepiness Scale were used to inquire about daytime sleepiness of patients. Overall retrospective chart review was performed on their sleep health data. Results The presence of nSOREMP was highly correlated with short mean sleep latency and high number of SOREMPs in MSLT. Subjects with nSOREMP also demonstrated higher percentage of N1 sleep, lower percentage of N2 sleep, and more frequent arousals in PSG. They also showed higher prevalence of cataplexy and human leukocyte antigen DQB1*06:02 positivity. Conclusion Subjects with nSOREMP showed more excessive daytime sleepiness and lower quality of sleep compared to subjects without nSOREMP. Our results suggest that nSOREMP might be a severity marker of narcolepsy.

Keywords

• multiple sleep latency test
• nocturnal sleep onset rapid eye movement
• sleep period
• nocturnal polysomnography
• narcolepsy
• cataplexy