Sleep Disorders: What Is Hypersomnia?

Hypersomnia is a condition marked by excessive daytime sleepiness. People who have hypersomnia can fall asleep at any time; for instance, at work or while driving. They may also have a lack of energy and trouble thinking clearly.

According to the National Sleep Foundation, up to 40% of people have some symptoms of hypersomnia from time to time.

What Causes Hypersomnia?

There are several potential causes of hypersomnia, including:

• The sleep disorders narcolepsy (daytime sleepiness) and sleep apnea (interruptions of breathing during sleep)
• Not getting enough sleep at night
• Being overweight
• Drug or alcohol abuse
• A head injury or a neurological disease, such as multiple sclerosis
• Prescription drugs, such as tranquilizers
• Genetics (having a relative with hypersomnia)

Reviewed by The Sleep Medicine Center at The Cleveland Clinic.