What Is Type 2 Narcolepsy?
Narcolepsy is a sleep disorder that causes overwhelming sleepiness during the day. It is usually diagnosed between the ages of 10 and 30 and is a lifelong disorder. There are 2 main types of narcolepsy: type 1 and type 2. One key difference is that type 2 does not have cataplexy. Cataplexy is the loss of muscle control caused by a strong emotion.1-3
Diagnosing type 2 narcolepsy is hard. Doctors must first rule out other common sleep problems. Common diagnosing tools are the polysomnogram (PSG) and the multiple sleep latency test (MSLT). However, many type 2 diagnoses made by MSLT are reversed.1,3
The cause of type 2 narcolepsy is unknown. There is no cure. Treatments to control symptoms are available. You may be given drugs to keep you alert. There are also lifestyle changes you can make to help you have the best quality of life.
What are the differences between type 1 and type 2 narcolepsy?
Narcolepsy is marked by excessive sleepiness and the inability to control the urge to sleep. A key symptom of type 1 narcolepsy is cataplexy. This symptom is not present in type 2 narcolepsy. People with type 1 narcolepsy also usually have low levels of a brain chemical called hypocretin, or orexin. People with type 2 narcolepsy do not usually have low hypocretin.1,4
Type 2 narcolepsy presents like idiopathic hypersomnia (IH). IH is the irresistible urge to sleep daily. Cataplexy is not a symptom of type 2 narcolepsy or IH, so doctors may struggle to tell the 2 conditions apart. One difference is that narcolepsy usually presents with sleep fragmentation while IH does not. Sleep fragmentation means you have trouble staying asleep.3
What are the brain differences in type 1 and type 2 narcolepsy?
A 2018 study used fluorodeoxyglucose positron emission tomography (FDG-PET) scans to look at the brains of narcoleptics. People with type 1 narcolepsy can have hypermetabolism, especially during cataplexy. This means the brain is very active.5,6
Compared to people with type 1 narcolepsy, people with type 2 narcolepsy had less hypermetabolism on their brain scans. Overall, the study showed people with type 2 narcolepsy had less severe symptoms and not as many brain-scan anomalies.5,6
What are the challenges of diagnosing narcolepsy?
1 out of every 3 Americans feels like they do not get enough sleep. However, there is a difference between being sleep deprived and having a sleep disorder.3
Narcolepsy is hard to diagnose because the symptoms of many sleep disorders are similar. Doctors use the following to rule out other sleep disorders and diagnose narcolepsy:3
- Excessive daytime sleepiness
- Sleep paralysis
- Hallucinations when falling asleep
What tests are used to diagnose narcolepsy?
You may take two sleep tests. These tests help figure out when you go into rapid eye movement (REM) sleep and how fast you fall asleep. The two tests are:2,7,8
- Polysomnography – This sleep study records vital signs and brain activity during an overnight stay at a sleep center. It can determine if your sleep cycles, including REM sleep, are interrupted and why.
- Multiple sleep latency test – This is called a nap test. You are given the chance to nap several times during this test. Doctors measure your sleep latency, or how fast you fall asleep, during these naps. They also look to see when and if you go into REM sleep.
PSG helps rule out other sleep disorders like sleep apnea. The MSLT helps determine if you have narcolepsy. People with narcolepsy have a positive MSLT. This means they fall asleep fast (less than 8 minutes) and go into REM sleep within 15 minutes. Compared to people with type 1 narcolepsy, people with type 2 narcolepsy have been shown to have less REM sleep and may take longer to fall asleep.2,5
Limitations of the Multiple Sleep Latency Test
A 2018 study looked at how reliable the MSLT was for diagnosing type 2 narcolepsy. Many people who had a positive MSLT and were diagnosed with type 2 narcolepsy were given the test again, and the diagnosis was changed. Similar results have been seen in other studies. This test is more reliable for type 1 narcolepsy.9
How is type 2 narcolepsy treated?
There is no cure for narcolepsy, but drugs can treat symptoms. The most common complaint from people with narcolepsy is daytime sleepiness. Your doctor may give you a stimulant to keep you awake. A common stimulant is modafinil (Provigil®), but amphetamines may be used. Current clinical trials are studying which drug is better for type 2 narcolepsy.2,4,10
Lifestyle changes may control narcolepsy symptoms
Staying on a regular sleep schedule is key. Taking scheduled naps may also help deter daytime sleepiness. Many people aim for 20-minute naps throughout the day. Limit caffeine and alcohol, as these can alter your sleep pattern. Daily exercise has also been shown to lessen symptoms.2,4
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