Hypersomnia and narcolepsy are sleep disorders. The two are often mistaken for each other because they are characterized by the same main symptom: excessive daytime sleepiness. Even scientists have noted that certain types of narcolepsy look very similar to hypersomnia on some tests.
Despite their similarities, the two are different disorders. They have different symptoms and causes, and they are also sometimes treated differently.
Understanding the differences between hypersomnia and narcolepsy can help you receive the correct diagnosis and treatment.
Hypersomnia means too much sleep. This sleep disorder can cause people to sleep for too long and be excessively tired during the day.
There are several types of hypersomnia. Idiopathic hypersomnia (IH) is the type of hypersomnia most often confused with narcolepsy. Idiopathic hypersomnia is a form of hypersomnia that is not related to any other condition or caused by any medication.
Although excessive daytime sleepiness is shared between IH and narcolepsy, other symptoms unique to idiopathic hypersomnia include:
Although these are the only two symptoms required for a diagnosis of IH, many people with the disorder also experience:
One of the major differences between narcolepsy and hypersomnia is the causes of the disorders.
Researchers do not yet know exactly what causes idiopathic hypersomnia. It is known to be a disorder of the nervous system, but the exact mechanisms at work that cause IH are still being investigated.
Some people diagnosed with IH have been found to overproduce a particular substance that acts on the brain like a sleeping pill or anesthetic (reduces pain sensitivity). People who overproduce this substance have enhanced GABA activity in the brain. GABA, or γ-aminobutyric acid, is the key neurotransmitter that promotes sleep.
Beyond this, researchers do not know what causes IH, though there appears to be a hereditary connection in 33 percent of cases of the disorder.
Like IH, narcolepsy is a sleep disorder.
People diagnosed with narcolepsy (and IH) usually exhibit excessive daytime sleepiness. They may struggle to stay awake consistently throughout the day — when the urge comes upon them to sleep, it is nearly impossible to resist. In fact, people with narcolepsy often fall asleep at unexpected times or in unusual places or positions.
Because narcolepsy interrupts the sleep-wake cycle, people with this diagnosis may also have trouble sleeping throughout the night.
The characteristic symptoms of narcolepsy include:
There are also other symptoms that some, but not all, people with a narcolepsy diagnosis may exhibit.
Cataplexy refers to a sudden loss of muscle tone. People with cataplexy may slur their speech, fall over, or experience other muscular symptoms. This loss of muscle tone is also usually associated with feeling a strong emotion, either positive or negative.
Narcolepsy with cataplexy is called type 1 narcolepsy. Type 2 narcolepsy does not include cataplexy.
Narcolepsy is often accompanied by sleep paralysis — a temporary inability to speak and/or move as one is falling asleep or waking up. These episodes mimic the paralysis that normally occurs only during REM sleep.
Hallucinations — seeing, hearing, or otherwise experiencing things that aren’t there — can occur upon falling asleep and awakening in people with narcolepsy. These hallucinations seem to be tied to experiences that usually occur during REM sleep being inappropriately combined with a waking brain.
Type 1 narcolepsy is linked to low levels of hypocretin. Hypocretin is a chemical messenger used by a part of the brain (the hypothalamus) to help the brain stay awake. In people with a diagnosis of narcolepsy, neurons containing hypocretin degenerate and die. The death of these neurons lowers a person’s alertness level and can cause the unusual REM cycles that people with narcolepsy experience.
There is some evidence that narcolepsy can be inherited. However, the chances of passing it on seem to be around 1 percent.
Less is known about the biological cause of type 2 narcolepsy. One theory is that type 2 narcolepsy is caused by less severe injury to the neurons of the hypothalamus than occurs in type 1 narcolepsy.
The process of diagnosing both narcolepsy and idiopathic hypersomnia is the same.
Diagnosis of both idiopathic hypersomnia and narcolepsy usually begins with a visit to the doctor. The doctor will start by asking about your recent sleep history, as well as any symptoms you’re experiencing during the day or at night.
Most experts in sleep medicine will also require people to keep a log of their sleep for a week or two. Some experts in sleep medicine will have a person wear an actigraph. This is a device that monitors human sleep/wake cycles to collect data about their sleep. It measures your movement during sleep and wake, which can indicate how much you are sleeping and the quality of the sleep you’re getting.
In order to diagnose hypersomnia or narcolepsy, doctors will use certain tests to collect data about your sleep.
For this test, you will have to stay overnight at a sleep laboratory and sleep with electrodes attached to your scalp. The test looks at the activity of your brain, heart, muscles, eyes, and lungs during the night.
A multiple sleep latency test (MSLT) is also conducted at a lab, but unlike polysomnography, it takes place during the day. It should be performed on the day after the polysomnogram.
During an MSLT, you’ll be required to take four to five naps, each spaced two hours apart. Experts in sleep medicine will measure how long it takes you to fall asleep and how fast you enter into the REM stage once you are asleep.
Although the process of diagnosis is similar, receiving a differential diagnosis of idiopathic hypersomnia or narcolepsy depends on the characteristics of your symptoms.
People with IH usually show:
People who receive a diagnosis of narcolepsy often show:
Using your self-reported symptoms and diagnostic testing, your doctor will be able to determine which sleep disorder you have, allowing them to recommend or prescribe the proper treatments.
Some of the treatments for idiopathic hypersomnia and narcolepsy overlap, although there are a few reserved for narcolepsy alone.
Most medications used to treat IH are off-label. This means that the medications have not necessarily been tested extensively on people diagnosed with IH, in particular.
With that in mind, read on to learn about treatments for idiopathic hypersomnia and narcolepsy.
Both Provigil (modafinil) and Nuvigil (armodafinil) are stimulants that help combat excessive daytime sleepiness. While taking these medications, it’s important to watch for side effects like dizziness, headaches, and nausea.
These medications may not be as effective for people diagnosed with IH as they are for those diagnosed with narcolepsy.
Other forms of stimulants, including Daytrana (methylphenidate) and Dexedrine (dextroamphetamine), can also help fight excessive daytime sleepiness. Despite being a different class of stimulant, they may have similar side effects to those sometimes caused by Provigil and Nuvigil.
Improving sleep hygiene through practices like going to bed at the same time every night, avoiding blue light before bed, and not consuming substances that interfere with sleep (like caffeine, alcohol, or other medications) may help people optimize their sleep.
Many experts in sleep medicine recommend cognitive behavioral therapy (CBT) for both idiopathic hypersomnia and narcolepsy. This will not treat the condition and cannot replace medications prescribed for narcolepsy or IH, but it can help people deal with some of the challenges that may accompany sleep disorders, such as their effects on your mood and daily life.
In addition to the treatments listed above, some may be used for narcolepsy, in particular. Some drugs used to treat narcolepsy include:
Because people with narcolepsy need to sleep often, scheduling naps may help them avoid or reduce instances of falling asleep unintentionally.
MyNarcolepsyTeam is the social network for people living with narcolepsy and their loved ones. Members regularly share their stories, ask for advice, and offer tips to help others live their best with narcolepsy.
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