Narcolepsy
Narcolepsy is a chronic central disorder of hypersomnolence marked by irresistible, recurrent daytime sleep attacks, most often from loss of orexin (hypocretin) producing neurons in the lateral hypothalamus; cataplexy, when present, is considered pathognomonic. Diagnosis follows a normal overnight polysomnogram and a multiple sleep latency test showing shortened sleep latency and rapid sleep-onset REM. Manage first with scheduled naps and sleep hygiene, then a wakefulness-promoting agent such as modafinil, adding pitolisant or sodium oxybate specifically for cataplexy.
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What this article covers
- Overview
A central disorder of hypersomnolence: narcolepsy is chronic, irresistible daytime sleepiness with recurrent, rapid-onset sleep attacks that intrude on wakefulness despite the patient feeling…
- Epidemiology
Onset in young adulthood: narcolepsy typically begins before age 30.
- Risk factors
Carriage of the associated human leukocyte antigen allele noted above is the genetic association.
- Pathophysiology
Orexin (hypocretin) deficiency in the lateral hypothalamus is the central mechanism, producing a dysregulated sleep-wake cycle and overwhelming, rapid-onset sleepiness.
- Clinical features
Diagnostic criteria: excessive daytime sleepiness with recurrent, rapid-onset, overwhelming sleepiness at least 3 times a week for at least 3 months, despite the patient feeling well-rested on…
- Differential diagnosis
Obstructive sleep apnea: witnessed apneas, loud snoring, and obesity, confirmed by an apnea-hypopnea index at or above 5 events per hour on polysomnography (PSG) (mild is 5 to 14 per hour); the…
- Diagnosis
The diagnosis rests on the clinical frequency-duration criteria or a confirmatory hypocretin (orexin) result: excessive daytime sleepiness with recurrent sleep attacks at least 3 times a week for at…
- Management
First, start scheduled daytime naps and sleep hygiene, and counsel on the danger of drowsy driving: this is the best initial measure for narcolepsy regardless of severity, before adding medication.
- Complications
Motor vehicle and occupational accidents from sleep attacks and drowsy driving, the reason every patient is counseled about the danger of driving.
- Prognosis
There is no cure; every agent is continuation or maintenance therapy, so treatment targets symptom control rather than resolution.
- Prevention
Maintain 7 to 8 hours of nightly sleep opportunity and a regular sleep-wake schedule, to limit superimposed insufficient sleep from worsening daytime sleepiness.
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Related articles
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Sleep disorders are sorted by which of three complaints a patient presents with: difficulty initiating or maintaining sleep, excessive daytime sleepiness, or abnormal behavior during sleep. Diagnosis proceeds from history, sleep diary, and bed-partner account through actigraphy to polysomnography and, when hypersomnolence is unexplained, a multiple sleep latency test. Management is complaint-specific: cognitive behavioral therapy for insomnia, airway pressure for sleep apnea, stimulants for narcolepsy, iron and a dopamine agonist for restless legs syndrome, and safety measures with melatonin or clonazepam for parasomnias.
- Insomnia
Insomnia is difficulty with sleep initiation, maintenance, or quality despite adequate opportunity for sleep, with daytime dysfunction; it becomes chronic insomnia disorder once symptoms occur at least 3 nights per week for at least 3 months. Treat first-line with cognitive behavioral therapy for insomnia, reserving hypnotics such as zolpidem, eszopiclone, or low-dose doxepin for refractory or short-term use.
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- Major depressive disorder
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