Narcolepsy: Causes, symptoms and medications

Sleep disturbances during the day may be a sign of narcolepsy. It can take eight to 10 years to recognize and diagnose narcolepsy. This is because signs of narcolepsy are similar to other illnesses, such as infections, certain thyroid diseases, drug and alcohol use, and other medical or sleep disorders. In school-age children and teens, narcolepsy has been mistaken for learning problems, seizure disorder or laziness. Although underdiagnosed, narcolepsy is still thought to be rare, only affecting 1 in every 1,000 to 3,000 people.

Narcolepsy is a sleep disorder defined by excessive, uncontrollable daytime sleepiness, often accompanied by a sudden, temporary loss of muscle tone or weakness. Individuals with the condition may experience "sleep attacks" in unusual circumstances, such as when walking, talking, eating or engaging in other activities. Most people with narcolepsy have difficulty sleeping at night. 

The usual cause of narcolepsy with cataplexy (muscle weakness) is low hypocretin levels. Hypocretin, a chemical in the brain, regulates wakefulness and rapid eye movement (REM) sleep. Also, certain people are born with genes that put them at risk for narcolepsy, and the condition is later triggered by any combination of factors, including infection, brain injury or an autoimmune disorder. Environmental toxins, such as heavy metals, pesticides, weed killers or secondhand smoke, may trigger narcolepsy. The cause of narcolepsy without cataplexy is unknown, but injuries to the hypothalamus and brain stem, tumors and stroke may be possible contributing factors. 

Narcolepsy is considered a neurologic disorder, but it may also be triggered as an autoimmune response. An infection, such as the H1N1 influenza virus, can trigger the immune system to attack the cells that produce hypocretin instead of the infection. The loss of hypocretin in the brain allows a person to suddenly enter REM sleep directly from the awake state. 

Normally, sleep progresses through stages: A person goes from awake to light sleep to deep sleep and back to light sleep before entering REM sleep, which occurs approximately 80–100 minutes into the sleep cycle. 

Narcolepsy type 1 or narcolepsy with cataplexy is characterized by mild to moderate daytime sleepiness and loss of voluntary muscle control of various degrees (partial or complete cataplexy) from weakness to falls. Cataplexy is triggered by intense emotions, such as joking, laughing, surprise or anger. Narcolepsy typically begins between the ages of 15–25 but can be identified at any age. 

Narcolepsy type 2, or narcolepsy without cataplexy, has all the characteristics of narcolepsy type 1 without the episodes of muscle weakness triggered by intense emotions. Type 2 narcolepsy is typically less severe. 

People with either type of narcolepsy may experience vivid hallucinations upon falling asleep, or they may wake up experiencing frightening visual, tactile or auditory sensations. Sleep paralysis with the inability to move for several minutes after awakening can be frightening, especially when accompanied by these hallucinations. Individuals may have some but not all of these symptoms with narcolepsy. 

Other potential features include fragmented sleep or other sleep disorders, such as obstructive sleep apnea, restless leg syndrome and REM sleep behavior disorder. Narcolepsy can be further complicated by obesity and psychiatric diagnoses. 

Anyone with chronic daytime sleepiness should see a healthcare provider to assess for narcolepsy. It is a good idea to start a sleep diary prior to your appointment. Record how easy it is to fall and stay asleep, how much sleep you get each night, and how alert you feel during the day. Include additional information, such as experiences with hallucinations when falling asleep, being unable to move when first waking or falling asleep, muscle weakness when laughing and falling asleep when you did not intend to do so.

A healthcare provider can make an assessment through your medical history, sleep history, a physical exam and neurologic exams. Other tests may include a polysomnogram (PSG) or overnight sleep study and a multiple sleep latency test (MSLT), which is initiated one and a half to three hours after the PSG.

The MSLT covers four or five opportunities to nap for 15–20 minutes while checking for the onset of REM periods. A finding of REM sleep during two or more of the naps, and falling asleep in under eight minutes, are criteria for the diagnosis of narcolepsy. The MSLT may have false negatives or positives 20% to 30% of the time, in which case the test may be repeated.

A laboratory test measuring the hypocretin level in cerebral spinal fluid can be helpful in certain clinical situations. Type 2 narcolepsy can be more difficult to diagnose compared to type 1 due to the absence of cataplexy and because sleepiness can occur as a result of other sleep disorders or conditions. 

Narcolepsy medication includes stimulant medications, selective serotonin reuptake inhibitors, tricyclic antidepressants and sodium oxybate.

Stimulant medications, such as modafinil (Provigil) or armodafinil (Nuvigil), stimulate the central nervous system. These medications are not as addictive as older stimulants, such as Aptensio XR, Concerta, Ritalin and other amphetamine drugs. The older stimulants have been shown to be very effective for narcolepsy but may also cause side effects such as nervousness and heart palpitations. 

Other medications for narcolepsy include selective serotonin reuptake inhibitors or serotonin and norepinephrine reuptake inhibitors, such as fluoxetine (Prozac) and venlafaxine (Effexor XR), which work to suppress REM sleep, helping with cataplexy symptoms, hallucinations and sleep paralysis. Possible side effects include weight gain, insomnia and digestive problems. Antidepressants such as protriptyline (Vivactil), imipramine and clomipramine (Anafranil) treat cataplexy. Side effects include dry mouth and lightheadedness.

Allergy and cold medications should be avoided with narcolepsy as they can cause drowsiness.

Driving a car or operating machinery may pose serious safety risks for people with narcolepsy, as they may fall asleep or lose muscle control and have an accident. Safety measures include taking naps before driving, frequently stopping to stretch and walk during long drives and having others in the car to keep you engaged.  

The Americans with Disabilities Act requires employers to provide reasonable accommodations for all employees with certain health conditions such as narcolepsy. You may want to choose a flexible work schedule to allow time for naps. A job with frequent interactions with coworkers may also be optimal. People with narcolepsy may be better suited with jobs close to home that require less or no driving. Education, self-awareness and counseling or support groups can help to relieve fear, anxiety and depression, and stress while maintaining a safe, productive daily life. 

Clinically reviewed and updated by Julie McDaniel, MSN, RN, CRNI, September 2022.