Causes
Most people with narcolepsy type 1 have low levels of hypocretin (orexin), a brain chemical that promotes wakefulness, likely because the immune system attacks the cells that produce it. Narcolepsy type 2 causes similar sleepiness without cataplexy, and its cause is less well understood. Daytime sleepiness that is not narcolepsy is more common and can stem from untreated sleep apnea, shift work, restless legs, sedating medications, thyroid disease such as hypothyroidism, or mood conditions such as depression.Symptoms
- Excessive daytime sleepiness: The defining symptom — an irresistible need to sleep, often in brief "sleep attacks."
- Cataplexy: Sudden, brief muscle weakness triggered by strong emotion such as laughter — knees buckling or the jaw going slack — with the person remaining awake. This occurs only in type 1 narcolepsy.
- Sleep paralysis: A temporary inability to move or speak while falling asleep or waking.
- Vivid dream-like hallucinations: Occurring at sleep onset or on waking.
- Fragmented nighttime sleep: Despite daytime sleepiness, nighttime sleep is often interrupted.
Diagnosis
Evaluation starts with a careful history, a review of medications, and often blood tests to exclude conditions like thyroid disease and anemia that cause fatigue. When narcolepsy is suspected, an overnight sleep study followed the next day by a multiple sleep latency test — a series of scheduled naps that measures how quickly you fall asleep and whether you enter dream sleep abnormally fast — confirms the diagnosis and rules out sleep apnea as the cause.Treatment
There is no cure, but most people achieve good control with a combination of medication and habits.- Wake-promoting medications: Modafinil or armodafinil are common first choices; newer options include pitolisant and solriamfetol. Traditional stimulants are sometimes used when these are not effective.
- Medications for cataplexy: Certain antidepressants and sodium oxybate taken at night can reduce cataplexy and improve nighttime sleep.
- Scheduled naps: One or two brief planned naps a day can dramatically improve alertness.
- Sleep hygiene: A consistent sleep schedule, avoiding alcohol and heavy meals before bed, and regular exercise support treatment. Overlapping pain or fatigue conditions such as fibromyalgia should also be addressed.