Loss of lateral hypothalamic neurons, which produce hypocretin-1 and hypocretin-2 (i.e. orexin A and orexin B) → severe hypocretin (orexin) deficiency → dysregulation of sleep-wake cycles
Excessive daytime sleepiness: Affected individuals experience an irresistible urge to sleep and sudden, short sleep attacks (< 30 minutes), which may occur in inappropriate situations (e.g., while driving a car).
Cataplexy: sudden muscle weakness in a fully conscious person, triggered by strong emotions (e.g., laughing, crying)
Sleep paralysis: Complete paralysis occurs for 1–2 minutes after waking or before falling asleep (either during a nocturnal or narcoleptic sleep episode, i.e., begins or ends with REM sleep)
Sleep hallucinations
Hypnagogic hallucinations: vivid, often frightening visual or auditory hallucinations that occur as the patient falls asleep
Hypnopompic hallucinations: experienced while waking up (less common than hypnagogic hallucinations)
Diagnostics
Treatment
General measures
Optimize sleep hygiene.
Ensure regular sleep periods during the night.
Avoid substances that disturb the sleep-wake cycle (e.g., alcohol, antipsychotics, opiates).
Consider scheduled naps throughout the day to reduce the urge to sleep.
Medical therapy
First-line medications
Modafinil: a nonamphetamine CNS stimulant
Nighttime sodium oxybate: a sodium salt of gamma hydroxybutyric acid
Help control daytime sleepiness by improving nighttime sleep.