Hypersomnia: Symptoms, Treatment & Causes


Written by Alison Deshong

Reviewed by Dr. Michael Breus

Our Editorial Process

Medical Disclaimer: The following content should not be used as medical advice or as a recommendation for any specific supplement or medication. It is important to consult your health care provider prior to starting a new medication or altering your current treatment.

Table of Contents

Hypersomnia is a rare sleep disorder characterized by a relatively common symptom: excessive daytime sleepiness. A person with hypersomnia feels very tired during the day, even after getting enough sleep at night.

People with hypersomnia have a hard time staying awake throughout the day, making it difficult for them to do their usual daytime activities like working or going to school. Hypersomnia may be treated by medication or by addressing an underlying condition. 

Key Takeaways


    • Hypersomnia symptoms include excessive sleepiness, difficulty waking, and prolonged sleep episodes.
    • Consult with a healthcare professional for an accurate diagnosis.
    • Treatments for hypersomnia involve medications, lifestyle changes, and behavioral therapies.
    • Manage hypersomnia daily with regular naps, physical activity, and emotional support.

What Is Hypersomnia?

Hypersomnia is a condition in which people feel excessive daytime sleepiness and their symptoms can’t be better explained by another, more common sleep disorder. Hypersomnia is part of a family of sleep disorders including narcolepsy.

Hypersomnia is sometimes confused with hypersomnolence. Hypersomnolence refers to the symptom of excessive daytime sleepiness. By contrast, hypersomnia is a specific sleep disorder that causes hypersomnolence. 

People with hypersomnia tend to first develop symptoms as teenagers, although the age at first symptoms can range from 10 to 30 years. It may take years after the first appearance of symptoms for a person to receive a formal diagnosis of hypersomnia.

Medical experts aren’t sure exactly how many people are affected by hypersomnia, though it appears to be relatively rare. But excessive daytime sleepiness itself is fairly common. Up to 1 in 4 people may deal with this symptom at some point in their lives. 

Doctors typically diagnose a person with hypersomnia after they have ruled out more common causes of daytime sleepiness. The most common cause is simply a lack of sleep, also called sleep deprivation. Other possible causes include:

  • Sleep disorders like sleep apnea
  • Depression and other mental health conditions
  • Certain medications
  • Medical disorders such as diabetes and hypothyroidism

While hypersomnia can negatively impact a person’s social and professional life, this sleep disorder doesn’t usually cause serious health complications. Sleep experts recognize several different types of hypersomnia, including idiopathic hypersomnia and hypersomnias associated with factors like medications and health conditions.

Idiopathic Hypersomnia

When doctors are unable to point to a specific cause of a condition, they may say that the condition is “idiopathic.” Idiopathic hypersomnia is hypersomnia that can’t be attributed to medication, mental health problems, or other external causes. Researchers still don’t fully understand how idiopathic hypersomnia develops or what might cause it.

Doctors refer to idiopathic hypersomnia as a diagnosis of exclusion. This means that doctors only give this diagnosis to someone when they can eliminate all other possible causes of excessive daytime sleepiness.

Other Hypersomnias

Sleep experts classify hypersomnias that are caused by external factors as “other hypersomnias.” Causes of other hypersomnias can include physical and mental health conditions, as well as some prescription or recreational drugs. As with idiopathic hypersomnia, other hypersomnias typically cause excessive daytime sleepiness.

A doctor must still rule out other common causes of daytime sleepiness before they can diagnose one of these hypersomnia variants. But the treatment plan for other hypersomnias usually hinges on identifying and addressing the underlying cause.

What Are Hypersomnia Symptoms?

The main symptom of hypersomnia is persistent daytime sleepiness, despite a person being able to consistently get enough sleep. This daytime sleepiness is severe enough to interfere with a person’s day-to-day life. Signs of excessive daytime sleepiness include:

  • Feeling extremely tired throughout the day
  • Accidentally falling asleep
  • Trouble staying focused on important tasks
  • Difficulty generally functioning in daily life
  • Headaches and lightheadedness

Additionally, the chronic sleepiness of hypersomnia may cause a range of other sleep problems.

  • Long daytime naps: People with hypersomnia often nap at least five days per week for an hour or more each day. Unlike in narcolepsy, these naps do little to ease the feeling of extreme tiredness.
  • Excess sleep at night: The average adult needs at least seven hours of sleep each night, but some people with hypersomnia may sleep up to 14 hours. However, these long sleep times don’t improve their daytime sleepiness.
  • Trouble waking up: It’s normal to feel a bit slow right after waking up, but people with hypersomnia may wake in a more extreme state called sleep drunkenness. This causes disorientation and mood disturbances for an hour or more after waking up, either in the morning or from a long nap.
  • Sleep paralysis: While not as common, people with hypersomnia may also experience sleep paralysis or hallucinations while falling asleep. 

If you or someone close to you has noticed that you have signs of hypersomnia or excessive daytime sleepiness, talk with your doctor. They may be able to identify the cause of your sleepiness, and they can develop a treatment plan to control your symptoms.

What Causes Hypersomnia?

The underlying cause of idiopathic hypersomnia is still unknown, but it is not associated with an underlying medical issue or medication. There may be multiple factors at play, and researchers are still working to understand the possible causes. Current theories include:

  • An immune response resulting from a viral infection
  • Changes in neurotransmitters that affect sleep and tiredness
  • Changes in the brain’s size, thickness, or internal connections
  • One or more genes inherited from a person’s parents

Other hypersomnias are caused by external factors that lead to excessive daytime sleepiness. There are three types of hypersomnias with identifiable causes.

  • Hypersomnia due to a medical disorder: In rare instances, certain medical conditions — including diabetes, hypothyroidism, Parkinson’s disease, traumatic brain injuries, and brain tumors — can cause excessive daytime sleepiness.
  • Hypersomnia due to a medication or substance: Sedative medications and certain substances like alcohol, cannabis, and opiates are associated with excessive daytime sleepiness. Withdrawal from stimulants can also make a person overly tired. 
  • Hypersomnia associated with a psychiatric disorder: Several mental health conditions are closely related to sleep issues. Some people with depression or bipolar disorder may have bouts of extreme sleepiness during the day.

How Is Hypersomnia Diagnosed?

To diagnose hypersomnia, a doctor or sleep expert performs a comprehensive set of medical evaluations and compares the results to the diagnostic criteria laid out in the International Classification of Sleep Disorders.

  • Medical history: A detailed medical history can help a doctor consider sleep symptoms alongside a person’s preexisting conditions, current medications, lifestyle, and sleep habits.
  • Sleep log: A doctor may ask the person to keep a sleep log, which is a careful accounting of sleep habits over several days or weeks. This can help confirm self-reported sleep symptoms.
  • Physical exam and blood work: A comprehensive physical exam can be important for identifying undiagnosed conditions. This may include screening for depression and standard blood work.
  • Actigraphy: Actigraphy measures a person’s activity, including during sleep, through a monitor worn on the wrist. Through actigraphy, doctors can learn more about a person’s sleep habits and patterns.
  • Sleep study: A sleep study or polysomnography is an overnight medical test in a sleep lab. This test can help rule out more common sleep disorders that may be causing excessive daytime sleepiness like obstructive sleep apnea.
  • Multiple sleep latency test: A multiple sleep latency test (MSLT), also performed in a sleep lab, allows doctors to measure sleepiness objectively. 

Of these tests, polysomnography and MSLT are required to make the diagnosis of hypersomnia.

One of the key steps during hypersomnia diagnosis is to rule out other possible causes of sleepiness. Lack of sleep is the most frequent cause of excessive daytime sleepiness, but it is often missed. The doctor must also determine whether symptoms are due to excessive daytime sleepiness or to low energy or general fatigue caused by another condition.

Sleeping too much has been linked to many of the same health risks as sleep deprivation. A consistent sleep schedule is imperative to getting the right quantity of sleep and the best quality sleep.
Dr. Michael Breus

How Is Hypersomnia Treated?

Doctors typically treat idiopathic hypersomnia with medication, most often with drugs that promote wakefulness. Other hypersomnias are treated by addressing the underlying cause.

Research on drugs for treating idiopathic hypersomnia is limited. Many of the medications that doctors prescribe for hypersomnia are the same as those for related sleep disorders like narcolepsy. Researchers are also investigating medications targeting sleep pathways in the brain.

It’s important to work with your doctor to find a medication that improves your symptoms without causing too many side effects. Frequent follow-ups, at least every six months, can help ensure that your treatment plan stays on track.

For other hypersomnias, successful treatment depends on addressing the underlying issue. In these cases, the biggest hurdle can sometimes be narrowing down the cause. But taking the time to get the right diagnosis can improve a person’s hypersomnia symptoms as well as their overall health.

Tips for Coping with Hypersomnia

Lifestyle changes may not be the most effective way to treat hypersomnia. For example, people with hypersomnia don’t usually find that naps or sleeping longer at night prevent excessive daytime sleepiness.

However, there are a few important steps you can take to make sure you keep yourself and those around you safe. Until you’ve started a treatment plan, it’s a good idea to limit activities and substances that can aggravate your symptoms, including:

  • Driving a car or other vehicle
  • Operating heavy machinery
  • Engaging in potentially dangerous activities that require focus
  • Late-night work or social events
  • Alcohol
  • Medications that cause drowsiness

Dealing with hypersomnia can be frustrating. But it’s important to remember that symptoms tend to stay steady and aren’t associated with any major health complications. With proper treatment, most people with hypersomnia will notice long-lasting improvements.

About The Author

Alison Deshong

Staff Writer, Product Testing Team

Alison is a health writer with ample experience reading and interpreting academic, peer-reviewed research. Based in San Diego, she is published in the journal PLOS Genetics and the Journal of Biological Chemistry and has been a copywriter for SmartBug media. With a master’s degree in biochemistry from the University of California, Davis, she has nearly a decade of academic research experience in life sciences. She enjoys helping people cut through the noise to understand the bigger picture about sleep and health. Alison likes to stay active with rock climbing, hiking, and walking her dog.

  • POSITION: Stomach Sleeper
  • TEMPERATURE: Neutral Sleeper

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