What is narcolepsy?
Narcolepsy is a sleep disorder that affects around 200,000 Americans. Patients suffer from excessive sleepiness through the day. They often require naps through the day to be functional. It can greatly impact their daily routine and can make it difficult to perform simple tasks.
Narcolepsy is divided into two types:
- Narcolepsy Type 1, includes sudden onset muscle weakness (called cataplexy) in response to being startled, scared, or an emotional high or low. In rare cases the whole body is affected and patients “pass out.” In the majority of cases on a smaller muscle group is involved (like the hand or jaw or thigh) and consciousness is maintained.
- Narcolepsy Type 2, does not include cataplexy and makes up the majority of diagnoses
What causes narcolepsy?
The cause of narcolepsy isn’t fully understood. However, there are some patients who clearly lack a brain hormone (orexin/hypocretin) that is responsible for maintaining wakefulness in the brain. It is likely that early childhood infections, such as “mono,” can lead to autoimmune process where the parts of the brain responsible for orexin is damaged. There are known genetic mutations that can predispose patients to narcolepsy as well.
While rare, narcolepsy, and other disorders of excessive sleepiness, can also develop after an injury to certain parts of your brain. This can result from concussions, strokes, brain tumors, or traumatic brain injuries..
What are the symptoms of narcolepsy?
The most obvious symptom of narcolepsy is the excessive daytime sleepiness and a struggle to stay awake during the day. Patients with narcolepsy often find naps to be helpful, refreshing. This is the most common symptom and one that all people diagnosed with narcolepsy have. Other main symptoms of narcolepsy can include muscle weakness (cataplexy), hallucinations going to sleep or while waking, and sleep paralysis, or the inability to move after waking. Some patients even have fragmented sleep at night and suffer from
Additional symptoms of narcolepsy may include amnesia, outbursts during sleep, or body movements while sleeping.
How is narcolepsy diagnosed?
Narcolepsy is diagnosed in one of two ways.
- An overnight and the all day sleep study called a “mean sleep latency test” (MSLT)
- Sleep duration and sleep structure is monitored overnight and then patients are allowed to takes naps the next day at 2 hr intervals (8am, 10am, noon, etc).
- The study is looking for if the patient can nap each time, how quickly they fall asleep, and what stages of sleep they experience during the nap.
- Narcolepsy has a specific pattern that demonstrates 1) excessive sleepiness in spite of an adequate night sleep, 2) stages of sleep, such as REM, that should not be seen during quick naps
- Sleep duration and sleep structure is monitored overnight and then patients are allowed to takes naps the next day at 2 hr intervals (8am, 10am, noon, etc).
- Spinal tap or lumbar puncture: this test measures the orexin hormone levels in your spinal fluid. Unfortunately, not every patient with narcolepsy would have a low orexin level in their spinal fluid, but this test can be helpful for making the diagnosis if the MSLT cannot be performed.
How is narcolepsy treated?
Foundation of treatment, historically, has been amphatamine based stimulants to improve symptoms. However, new and better drugs to promote wakefulness have been created and can be used in combination with each other to improve symptom control. Better yet, a newer class of drugs called “oxybates”, have been developed and are very successful in the treatment of narcolepsy. Oxybates are, counterintuitively, sedatives that patients would take at night. In addition to promoting sleep, the oxybates provide “restorative” sleep that the patient’s with narcolepsy are not getting (in spite of how much they sleep) and reduce the daytime burden of sleepiness.