Narcolepsy type 1

Narcolepsy type 1 (NT1), also known as narcolepsy with cataplexy or narcolepsy-cataplexy syndrome, is a chronic neurological disorder caused by the loss of hypocretin (orexin)-producing neurons in the hypothalamus of the brain. Hypocretin is a neuropeptide critical for regulating wakefulness and the sleep-wake cycle. The destruction of these neurons is believed to result from an autoimmune process, strongly associated with the HLA-DQB1*06:02 allele. The disease primarily affects the central nervous system and disrupts the normal boundaries between sleep and wakefulness. The hallmark symptoms of narcolepsy type 1 include excessive daytime sleepiness (EDS), which is often overwhelming and irresistible, and cataplexy — sudden episodes of muscle weakness or paralysis triggered by strong emotions such as laughter, surprise, or anger. Other common features include sleep paralysis (temporary inability to move when falling asleep or waking up), hypnagogic or hypnopompic hallucinations (vivid dream-like experiences at sleep onset or upon awakening), and disrupted nighttime sleep. Patients may also experience automatic behaviors, where routine tasks are performed without conscious awareness. The diagnosis is confirmed by polysomnography followed by a multiple sleep latency test (MSLT) and, when available, measurement of cerebrospinal fluid hypocretin-1 levels, which are characteristically very low or undetectable in NT1. Onset typically occurs during childhood or adolescence, though it can present at any age. There is no cure for narcolepsy type 1, but symptoms can be managed with pharmacological and behavioral interventions. Excessive daytime sleepiness is treated with wake-promoting agents such as modafinil, pitolisant, or solriamfetol, and with stimulants such as methylphenidate or amphetamines. Cataplexy and other REM sleep-related symptoms are managed with sodium oxybate (gamma-hydroxybutyrate), antidepressants (particularly venlafaxine or selective serotonin reuptake inhibitors), or the lower-sodium formulation of oxybate. Scheduled naps and good sleep hygiene are important adjunctive strategies. Ongoing research is exploring immunotherapy approaches aimed at early disease modification.

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