Narcolepsy is a chronic neurological disorder that affects the sleep-wake cycle. It is characterized by excessive daytime sleepiness, sudden and uncontrollable episodes of falling asleep, and changes in muscle control, known as cataplexy. Other symptoms may include sleep paralysis, hallucinations, and disrupted nighttime sleep.

The exact cause of narcolepsy is not well understood, but it is thought to be related to a deficiency in the brain chemical hypocretin, which regulates sleep and wakefulness. This deficiency may be due to an autoimmune reaction, genetic factors, or brain injury.

Diagnosis of narcolepsy may involve a sleep study to monitor brain activity, heart rate, and muscle activity during sleep. The doctor may also perform a physical exam and review the person's medical history and symptoms.

Treatment options for narcolepsy may include medications such as stimulants to help manage excessive daytime sleepiness, and antidepressants or sodium oxybate to help manage cataplexy and other symptoms. Lifestyle changes such as regular sleep patterns, taking short naps during the day, and avoiding alcohol and caffeine may also be recommended to help manage symptoms.

While there is no cure for narcolepsy, treatment can help manage symptoms and improve quality of life. It is important for people with narcolepsy to work with a healthcare professional to develop a treatment plan that meets their individual needs.

The exact cause of narcolepsy is unknown. People with type 1 narcolepsy have low levels of the chemical hypocretin (hi-poe-KREE-tin). Hypocretin is an important neurochemical in your brain that helps regulate wakefulness and REM sleep.

Hypocretin levels are particularly low in those who experience cataplexy. Exactly what causes the loss of hypocretin-producing cells in the brain isn't known, but experts suspect it's due to an autoimmune reaction.

It's also likely that genetics play a role in the development of narcolepsy. But the risk of a parent passing this disorder to a child is very low — only about 1%.

Research also indicates a possible association with exposure to the swine flu (H1N1 flu) virus and a certain form of H1N1 vaccine that's currently administered in Europe, though it's not yet clear why.

Normal sleep pattern vs. narcolepsy

The normal process of falling asleep begins with a phase called non-rapid eye movement (NREM) sleep. During this phase, your brain waves slow considerably. After an hour or so of NREM sleep, your brain activity changes, and REM sleep begins. Most dreaming occurs during REM sleep.

In narcolepsy, however, you may suddenly enter into REM sleep without first experiencing NREM sleep, both at night and during the day. Some of the characteristics of narcolepsy — such as cataplexy, sleep paralysis and hallucinations — are similar to changes that occur in REM sleep, but occur during wakefulness or drowsiness.

There is no cure for narcolepsy, but medications and lifestyle modifications can help you manage the symptoms.

Medications

Medications for narcolepsy include:

• Stimulants. Drugs that stimulate the central nervous system are the primary treatment to help people with narcolepsy stay awake during the day. Doctors often try modafinil (Provigil) or armodafinil (Nuvigil) first for narcolepsy. Modafinil and armodafinil aren't as addictive as older stimulants and don't produce the highs and lows often associated with older stimulants. Side effects are uncommon, but may include headache, nausea or anxiety.
• Sunosi (solriamfetol) and pitolisant (Wakix) are newer stimulants used for narcolepsy, headache and anxiety. Pitolisant may also be helpful for cataplexy.
• Some people need treatment with methylphenidate (Aptensio XR, Concerta, Ritalin, others) or various amphetamines. These medications are very effective but can be addictive. They may cause side effects such as nervousness and heart palpitations.
• Selective serotonin reuptake inhibitors (SSRIs) or serotonin and norepinephrine reuptake inhibitors (SNRIs). Doctors often prescribe these medications, which suppress REM sleep, to help alleviate the symptoms of cataplexy, hypnagogic hallucinations and sleep paralysis. They include fluoxetine (Prozac, Sarafem) and venlafaxine (Effexor XR). Side effects can include weight gain, insomnia and digestive problems.
• Tricyclic antidepressants. These older antidepressants, such as protriptyline (Vivactil), imipramine (Tofranil) and clomipramine (Anafranil), are effective for cataplexy, but many people complain of side effects, such as dry mouth and lightheadedness.
• Sodium oxybate (Xyrem). This medication is highly effective for cataplexy. Sodium oxybate helps to improve nighttime sleep, which is often poor in narcolepsy. In high doses it may also help control daytime sleepiness. It must be taken in two doses, one at bedtime and one up to four hours later.
• Xyrem can have side effects, such as nausea, bed-wetting and worsening of sleepwalking. Taking sodium oxybate together with other sleeping medications, narcotic pain relievers or alcohol can lead to difficulty breathing, coma and death.

If you have other health problems, such as high blood pressure or diabetes, ask your doctor how the medications you take for your other conditions may interact with those taken for narcolepsy.

Certain over-the-counter drugs, such as allergy and cold medications, can cause drowsiness. If you have narcolepsy, your doctor will likely recommend that you avoid taking these medications.

Emerging treatments being investigated for narcolepsy include drugs acting on the histamine chemical system, hypocretin replacement, hypocretin gene therapy and immunotherapy, but further research is needed before any may be available in your doctor's office.