Narcolepsy and emotional experience: a review of the literature.

Narcolepsy, a chronic sleep disorder marked by excessive daytime sleepiness, cataplexy, and hallucinations, profoundly disrupts social, work, and emotional life. Cataplectic attacks are often triggered by emotions like laughter, surprise, or anger. Evidence points to dysfunctional interplay between the hypothalamus and amygdala, along with altered hypocretin levels, as underlying causes. People with narcolepsy-cataplexy may develop coping strategies to avoid emotional triggers, even during sleep, where they experience more vivid, bizarre, and frightening dreams than healthy individuals. This review synthesizes behavioral, neurophysiological, and neurochemical findings to clarify the complex link between narcolepsy and emotional experience, aiming to guide future research.

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Abstract

Narcolepsy is a chronic sleep disorder characterized by excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and sleep paralysis. This disease affects significantly the overall patient functioning, interfering with social, work, and affective life. Some symptoms of narcolepsy depend on emotional stimuli; for instance, cataplectic attacks can be triggered by emotional inputs such as laughing, joking, a pleasant surprise, and also anger. Neurophysiological and neurochemical findings suggest the involvement of emotional brain circuits in the physiopathology of cataplexy, which seems to depending on the dysfunctional interplay between the hypothalamus and the amygdala associated with an alteration of hypocretin levels. Furthermore, behavioral studies suggest an impairment of emotions processing in narcolepsy-cataplexy (NC), like a probable coping strategy to avoid or reduce the frequency of cataplexy attacks. Consistently, NC patients seem to use coping strategies even during their sleep, avoiding unpleasant mental sleep activity through lucid dreaming. Interestingly, NC patients, even during sleep, have a different emotional experience than healthy subjects, with more vivid, bizarre, and frightening dreams. Notwithstanding this evidence, the relationship between emotion and narcolepsy is poorly investigated. This review aims to provide a synthesis of behavioral, neurophysiological, and neurochemical evidence to discuss the complex relationship between NC and emotional experience and to direct future research.