What medical conditions are known to cause excessive daytime sleepiness?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Excessive daytime sleepiness (EDS) is often caused by sleep disorders such as sleep apnea, narcolepsy, or restless leg syndrome. It can also stem from underlying health conditions like depression, anxiety, hypothyroidism, or anemia. Additionally, poor sleep habits—including inconsistent bedtimes, screen use before bed, or insufficient sleep—are common contributors to EDS.

Because the causes vary widely, identifying the root of your sleepiness is the critical first step toward feeling better. A free, instant, online symptom check can help you pinpoint likely causes based on your specific symptoms and guide you on next steps—whether that's simple lifestyle changes or a conversation with a doctor. It takes just a few minutes and could save you weeks of guessing.

Reviewed for medical accuracy: 07/14/2026

Important Next Steps

Discover what causes excessive daytime sleepiness Learn if excessive sleepiness needs care today Find out if your sleepiness is serious See OTC options for daytime sleepiness Find a doctor for sleep disorders Understand home remedies for excessive daytime sleepiness Check likely causes of excessive daytime sleepiness

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Explanation

Excessive daytime sleepiness is when someone feels very sleepy during the day, even if they have had enough hours of sleep at night. Various medical conditions can cause excessive daytime sleepiness.

Some Medical Conditions That Can Cause Excessive Daytime Sleepiness:

Certain Sleep Disorders: One example of a sleep disorder is called sleep apnea -- this is when breathing stops and starts during sleep, causing poor sleep quality. A common type of sleep apnea is called obstructive sleep apnea, which can disrupt your rest and leave you feeling exhausted throughout the day.
Chronic Pain: Ongoing pain can disturb sleep, leading to daytime sleepiness.
Health Conditions That Can Cause Fatigue Or Low Energy: Numerous health conditions can cause someone to feel very tired (known as fatigue). For example, one cause of fatigue is anemia, which is when the number of red blood cells in the body is lower than normal. Another example is depression -- when someone is experiencing depression, they can have symptoms including mood changes as well as feeling sleepy and/or lacking energy. A third example is hypothyroidism (when the thyroid does not make enough thryoid hormone, which results in various symptoms including feeling tired all the time).

Keep in mind that a person's sleep habits may also contribute to feeling tired during the day. Sleeping at least 7 hours per day is recommended for most adults. Caffeine and/or alcohol near bedtime can also impair sleep at night. Maintaining good sleep hygiene is important for overall health and energy levels.

A healthcare provider can provide a personalized medical assessment to determine why you or someone you know may be experiencing excessive daytime sleepiness. If you're concerned about your symptoms and want to understand what might be causing your fatigue, try our free AI symptom checker to help identify potential causes. The appropriate medical treatment plan will depend on the cause of these symptoms. Also, if you or someone you know has mental health questions or concerns, some more help is available at 988lifeline.org.

(References)

Gandhi KD, Mansukhani MP, Silber MH, & Kolla BP. (2021). Excessive Daytime Sleepiness: A Clinical Review. Mayo Clinic proceedings, 33840518.
Pagel JF. (2009). Excessive daytime sleepiness. American family physician, 19275068.
Pérez-Carbonell L, Mignot E, Leschziner G, & Dauvilliers Y. (2022). Understanding and approaching excessive daytime .... Lancet (London, England), 36115367.

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