Excessive Daytime Sleepiness (Idiopathic Hypersomnia)

What is excessive daytime sleepiness?

Excessive daytime sleepiness is a sleep disorder that makes you feel very drowsy during the day, even after getting 10 or more hours of sleep at night. You often doze, nap, or fall asleep when you need or want to be awake and alert. This can be dangerous when you are driving a car or operating machinery. This disorder is also called idiopathic hypersomnia (IHS).

What is the cause?

The cause of this disorder is not completely known. It has been linked to having too much of a chemical in the brain that promotes sleep.

IHS is most common in teenagers and young adults. Your risk is greater if another family member has it.

What are the symptoms?

Symptoms may include:

  • Constant sleepiness
  • Taking naps regularly and still feeling sleepy
  • Long nighttime sleeping, over 10 hours
  • Trouble waking from a long sleep
  • Feeling groggy and confused when you wake up
  • Trouble focusing and remembering things

How is it diagnosed?

Your healthcare provider will ask about your symptoms and medical history and examine you. You may have tests to check for other possible causes of your symptoms, such as medicines or medical conditions such as narcolepsy, restless leg syndrome, or sleep apnea.

You will be asked to visit a sleep center to have tests such as:

  • Polysomnogram. This test records brain waves, muscle activity and movement, heartbeat, and breathing while you sleep.
  • Multiple sleep latency test (MSLT). This test shows how quickly you fall asleep. For the MSLT, you will be asked to take several naps during the test period.

How is it treated?

Your healthcare provider may give you medicine to decrease your symptoms and help you feel more alert.

How can I take care of myself?

Follow the full course of treatment prescribed by your healthcare provider. In addition:

  • Keep regular sleep times, including scheduled naps.
  • If you are sleepy, then you should not drive.
  • Avoid medicines such as sedatives or some antihistamines that may cause sleepiness. Also avoid alcohol.
  • Ask your provider:
    • How and when you will hear your test results
    • If there are activities you should avoid
    • How to take care of yourself at home
    • What symptoms or problems you should watch for and what to do if you have them

Make sure you know when you should come back for a checkup. Keep all appointments for provider visits or tests.

You can get more information from:

Developed by RelayHealth.
Adult Advisor 2015.1 published by RelayHealth.
Last modified: 2015-01-29
Last reviewed: 2014-12-16
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright ©1986-2015 McKesson Corporation and/or one of its subsidiaries. All rights reserved.

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