What Is Idiopathic Hypersomnia?

While the sleep disorder narcolepsy is commonly known and studied, its close cousin, idiopathic hypersomnia, is often overlooked and more challenging to diagnose.

A little-known neurologic condition, idiopathic hypersomnia is a debilitating sleep disorder that leaves people feeling excessively sleepy during the day, despite sleeping deeply and for unusually long periods of time.

Symptoms of Idiopathic Hypersomnia

Unlike individuals with narcolepsy, people with idiopathic hypersomnia do not have disturbed nighttime sleep or refreshing daytime naps. They may sleep deeply for as many as 15 hours every night, yet don’t feel refreshed. Some avoid daytime naps which can lead to more grogginess and fatigue afterwards.

Mornings are the toughest time of the day for people with this condition due to pronounced and prolonged difficulty waking up, a phenomenon known as “sleep inertia” or “sleep drunkenness.” Most require multiple alarms to wake up in the morning or more elaborate strategies combining sequential alarms placed in different locations and periodic stimulation from family or friends.

Other characteristics of the chronic condition, which develops over weeks or months, include:

— An uncontrollable desire to go back to sleep.

Brain fog.

— Poor memory.

Thinking clearly and carrying out basic tasks can be challenging. Schoolwork, jobs and relationships often suffer. People with idiopathic hypersomnia are twice as likely to have accidents behind the wheel than healthy individuals. The burden of disease is even heavier by the coexistence of anxiety and depression in many cases.

[See: Steps to Fall Asleep Fast.]

Diagnosing Idiopathic Hypersomnia

Symptoms often appear in mid-to-late teens or early twenties and persist throughout life. People with the condition often live without a correct diagnosis for a long time. The diagnosis may be overlooked because of assumptions that teenagers and young adults need more sleep than older adults, or it may be misinterpreted as laziness.

Making the diagnosis is complex and requires an overnight sleep study, called a polysomnogram, followed by a daytime nap test, called a multiple sleep latency test, performed in a sleep laboratory under optimized conditions (no prior sleep deprivation or alcohol, off medications that may confound testing). Insufficient slumber and other causes of excessive sleepiness must be excluded. Even then, the diagnosis may remain elusive due to known limitations of laboratory testing and the absence of a definitive disease biomarker.

Although it’s classified as a rare disorder by the National Institutes of Health, this condition may be more common than previously realized. Studies show that about one in 2,000 people has narcolepsy and about one in 10,000 has idiopathic hypersomnia.

However, the prevalence of both disorders is believed to be underestimated due to lack of awareness, inaccessibility of health care experts, cost of diagnostic testing and comorbid health issues including mood disorders and substance abuse.

[READ: How to Prepare for a Sleep Apnea Test.]

Causes of Excessive Sleepiness

Excessive sleepiness has many causes. In my world, it is associated with a host of sleep disorders, such as sleep apnea, restless legs syndrome and voluntary insufficient sleep. Excessive sleepiness can be induced by medications, illicit drugs and some medical and psychiatric disorders.

A 2012 study surveying 15,929 adult Americans found excessive sleepiness reported by 27.8% of the sample. Only 28% of these fatigued individuals reported routine napping and 17% falling asleep easily or without warning. Usual sleep duration was six hours or less in only 26% of cases, suggesting that chronic sleep deprivation was not a factor in most cases. After excluding all other sleep disorders that cause excessive sleepiness, the prevalence of a hypersomnia disorder was 1.5%, substantially greater than the known prevalence of narcolepsy and idiopathic hypersomnia combined.

The current population of the United States is more than 333,760,000. If the prevalence of hypersomnia disorders is indeed close to the above estimate of 1.5%, the affected population — excluding teens — would surpass 5,006,000 individuals. I don’t know about you, but I’m getting tired just thinking about it!

[READ: Does Melatonin Work for Sleep?]

Treatments for Idiopathic Hypersomnia

Medications approved for the treatment of narcolepsy, such as amphetamine, methylphenidate, modafinil and armodafinil, are used off-label for treatment. However, the efficacy of these for the symptoms of idiopathic hypersomnia has not been confirmed in clinical trials, and treatment produces only partial relief in most cases.

Drum roll please … A new medication could offer desperately needed wakefulness to those who live with this debilitating disorder. In August 2021, the Food and Drug Administration approved the first medication for idiopathic hypersomnia.

Results from a multi-center study showed that lower sodium oxybate, or LXB, demonstrated clinically meaningful improvements in excessive sleepiness and other symptoms of idiopathic hypersomnia in affected adults. Also approved for excessive sleepiness and cataplexy (sudden muscle weakness) in narcolepsy of patients 7 years of age and older, LXB is comprised of calcium, magnesium, potassium and sodium oxybates, and it was developed as an alternative to sodium oxybate due to the cardiovascular risk of high sodium content. Sodium oxybate was approved by the FDA for the treatment of cataplexy and excessive sleepiness in narcolepsy in 2002 and 2005, respectively, and is classified by the American Academy of Sleep Medicine as a first-line therapy for narcolepsy.

If you have experienced excessive daytime sleepiness at least three days a week for at least three months, talk to your health care provider to find out if your symptoms are due to a sleep disorder.

Here’s to a good night’s sleep and wide awake days.

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What Is Idiopathic Hypersomnia? originally appeared on usnews.com

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