Abstract
The causes of sleep disruption in patients with narcolepsy are not clearly identified. Possible causes include daytime sleep through planned or unplanned naps, impairment of the delta-wave generating mechanisms, and comorbid sleep disorders such as sleep disordered breathing and periodic leg movements (PLMs). PLMs have been proposed as one of the causes of increased arousal in narcolepsy. Two recent controlled studies have demonstrated increased prevalence of PLMs in narcoleptics compared to controls with an impact on sleep latency on multiple sleep latency test. At the present, the contribution of PLMs to the perceived sleep quality and daytime sleepiness in narcolepsy patients is not clear. The observation that PLMs arousals were significantly higher in the PLMs group suggests that reducing the frequency of PLMs may improve sleep architecture. The pathophysiology of narcolepsy may involve an abnormal cholinergic-dopaminergic interaction. Pharmacological agents that decrease dopaminergic release, such as gamma-hydroxybutyrate and neuroleptic-D2 receptor antagonists, have been shown to worsen PLMs. Additionally, dysfunction in the hypocretin/dopaminergic system is likely to be one of the mechanisms involved in the pathophysiology of narcolepsy, with alterations in arousal systems and sleep-related motor activation resulting in a large number of PLMs.