The Correlation between Clinical Variables and Sleep Onset Rapid Eye Movement Period Frequencies in Narcoleptic Patients

Abstract

Background and Objective A diagnosis of narcolepsy is defined by less than 8 minutes of mean sleep latency, and two or more sleep onset rapid eye movement periods on the Multiple Sleep Latency Test. This study examined the relationship between the sleep onset rapid eye movement period frequencies during Multiple Sleep Latency Test and narcoleptic symptom severity. Methods From March 2004 to August 2009, 126 patients suffering from excessive daytime sleepiness who visited the Sleep Disorders Clinic of St. Vincent’s Hospital at the Catholic University of Korea were tested by polysomnography and Multiple Sleep Latency Test. Subjects were divided into three groups according to the number of sleep onset rapid eye movement periods that appeared on the Multiple Sleep Latency Test. Symptom severity instruments included the Epworth Sleepiness Scale and the Stanford Center for Narcolepsy Sleep Inventory, and various sleep parameters. In addition, we performed human leukocyte antigen genotyping for human leukocyte antigen-DQB1*0602 on all patients. Results Among the three groups classified by the number of sleep onset rapid eye movement periods during Multiple Sleep Latency Test, we found no significant differences in demographic features, Epworth Sleepiness Scale, and most polysomnographic findings. However, we observed cataplexy, hypnagogic hallucination, sleep paralysis, and human leukocyte antigen-DQB1*0602 positivity more frequently in groups with higher sleep onset rapid eye movement period frequencies. In addition, the proportions of stage II sleep, REM sleep latency from polysomnography, and mean sleep latency and mean REM sleep latency from the Multiple Sleep Latency Test significantly decreased with increasing sleep onset rapid eye movement period frequency. Conclusions In this study, we demonstrated that sleep onset rapid eye movement period frequency during Multiple Sleep Latency Test correlated with sleep architecture, daytime symptom severity, and frequency of human leukocyte antigen-DQB1*0602 positivity in narcolepsy. Further studies are needed to explore the pathophysiology of narcolepsy associated with sleep onset rapid eye movement periods.

Keywords

• Narcolepsy
• Sleep onset rapid eye movement periods
• Cataplexy
• Sleep paralysis
• Hypnagogic hallucination