Sleep schedules and MSLT-based diagnosis of narcolepsy type 2 and idiopathic hypersomnia: Exploring potential associations in a large clinical sample

Differential diagnosis of narcolepsy type 2 and idiopathic hypersomnia relies on the frequency of sleep-onset rapid eye movement periods observed on the Multiple Sleep Latency Test. This study investigated whether variations in sleep schedules, particularly delayed sleep-wake patterns, contribute to the diagnostic distinction between narcolepsy type 2 and idiopathic hypersomnia. The study included 871 patients aged 18-39 years (316 with narcolepsy type 2, 555 with idiopathic hypersomnia). These patients were diagnosed based on MSLT results following polysomnography from November 2013 to November 2017. Patients' sleep habits, including bedtime and wake-up times on weekdays and weekends during the 2 weeks preceding the polysomnography/Multiple Sleep Latency Test, were assessed using self-reported sleep logs. A multivariate logistic regression analysis was conducted to identify factors associated with narcolepsy type 2 diagnosis. The analysis revealed that being male (p < 0.001), younger age (p < 0.001), shorter weekday sleep duration (p < 0.05), and a delayed weekday sleep midpoint time (p < 0.01) were significantly associated with a diagnosis of narcolepsy type 2. The study suggests that the conventionally fixed schedule of polysomnography and Multiple Sleep Latency Test administration may have contributed to the increased occurrence of sleep-onset rapid eye movement periods particularly in individuals with a delayed sleep-wake schedule.