Are You Just Tired, or Is It Excessive Daytime Sleepiness? Here’s Why It Matters

We all get tired and rundown at some point—you know that feeling where you want to change your “to-do” list to a “do-nothing” list, and just lie down and take a nap. But if you regularly find yourself struggling to stay awake during the day, it could be something more than simple grogginess. It could be excessive daytime sleepiness.

Excessive daytime sleepiness (EDS) is a medical condition where the need for sleep is so intense that it interferes with daily activities, even if you’ve gotten enough sleep at night, per a May 2021 clinical review in Mayo Clinic Proceedings¹. According to the review, as many as 1 in 3 U.S. adults report dealing with excessive sleepiness during the daytime.

“Excessive daytime sleepiness is a specific medical term for a strong desire or likelihood of falling asleep,” says Anne Marie Morse, DO, a board-certified pediatric neurologist with clinical and research interests in sleep medicine, and director of Pediatrics Neurology at Geisinger Medical Center in Pennsylvania. “People will have to fight to stay awake and experience inappropriate sleep during periods of wakefulness.”

Because EDS affects mood, memory, focus, attention, and productivity, it can have a big effect on quality of life, along with raising the risk for accidents and other health conditions, according to the NHS. EDS is also typically a symptom of another condition—meaning it can have numerous causes that take medical expertise to diagnose and treat, says Dr. Morse.

Read on to find out more about EDS, how it’s different from grogginess or fatigue, and what you can do if you think you’re dealing with it yourself.

Who does excessive daytime sleepiness primarily affect?

Regularly not getting enough sleep (that is, getting fewer than seven hours per night) puts you at risk for EDS, no matter the reason behind your lack of zzzs, says Nancy Foldvary-Schaefer, DO, director of the Sleep Disorders Center at the Cleveland Clinic Neurological Institute.“Insufficient sleep is the number one cause” of excessive daytime sleepiness, she says, adding: “Forty percent of adult Americans are chronically sleep-deprived.”

There are two different types of EDS: primary and secondary. Primary EDS (also known as primary hypersomnia) means the need to sleep is not a symptom or caused by another medical issue, but happens because areas of the brain and nervous system involved in sleep aren’t functioning properly, per the Cleveland Clinic. Some examples of primary EDS disorders include narcolepsy and Kleine-Levin syndrome (sometimes called “sleeping beauty syndrome”).

Secondary EDS—or EDS from another cause—is much more common than primary EDS, according to the American Academy of Family Physicians (AAFP). While these causes are sometimes broken down into “medical” and “nonmedical” categories, Dr. Morse says that’s not entirely accurate. “Everything is a medical cause because something is biologically causing” the need to sleep, she explains.

Some secondary causes of EDS include the following, per AAFP:

• Sleep disorders like obstructive sleep apnea, restless legs syndrome, or circadian rhythm sleep disorder
• Medical conditions that interrupt the sleep-wake cycle including stroke, cancer, and neurodegenerative conditions like Parkinson’s disease
• Mental health conditions, especially depression
• Some prescription and over-the-counter medications (including sleeping pills, opioids, and antihistamines)
• Behaviors that cause sleep deprivation, such as shift work, staying up too late, or jet lag

“It’s important not to normalize sleepiness. It’s not normal, it’s just common.” —Anne Marie Morse, DO

How is it different from simply being tired?

Fatigue, tiredness, or grogginess are all common, but they aren’t the same as having EDS, although the two conditions can co-exist, says Dr. Morse. For example, if you’re fatigued, you might feel run-down physically and mentally and not up to doing certain tasks, but not overly sleepy. But if you have EDS, you may need to nap multiple times during the day, even though you’ve slept enough at night, she explains. And because one of the causes of EDS is sleep deprivation, you might have an increased drive to sleep, too.

EDS can also affect your life beyond bouts of tiredness. It’s often associated with social and professional impairment, psychological distress, occupational and motor vehicle accidents, and interpersonal conflicts, says Dr. Foldvary-Schaefer.

“EDS invades all aspects of life,” says Dr. Morse. “You may be more irritable, depressed, or anxious. It can impair your ability to perform tasks, making you more prone to errors and more frustrated when making errors.” Because those with EDS are prone to mood instability and irritability, the condition also affects relationships, she adds.

There are potential risks of daytime sleepiness, too

EDS doesn’t just affect quality of life—it increases the risk of accidents and other health issues. EDS is a major cause of work-related injury and is estimated to be the cause of almost one-fifth of all motor vehicle accidents in the U.S., per a January 2018 article in the Journal of the Missouri State Medical Association². Along with the risk of falling asleep behind the wheel, EDS increases reaction time, which can affect a driver’s ability to quickly correct a vehicle or keep a vehicle within a lane, according to a September 2023 article in Sleep.

“EDS causes lapses in judgment and awareness and puts you at risk, whether you work in an office or are a pro athlete,” says Dr. Morse. “Driving with EDS has the same reaction-time risk and legal consequences as driving under the influence of alcohol. If you wouldn’t let your friend leave buzzed, don’t let your friend leave tired,” she adds.

Dr. Morse also says that when it comes to driving, people often think they can “outsmart” sleepiness—but they can’t. “People will turn up the music or air conditioning or open the car windows, but studies have found while subjectively people might feel more alert, objectively they’re not,” she adds.

Likewise, EDS can also take a toll on your health. Sleep is crucial to the health of all the body’s systems and insufficient sleep raises the risk of diabetes, obesity, mental health disorders, a weakened immune system, and hormone abnormalities, per the National Library of Medicine. EDS is also associated with an increased risk of cardiovascular disease and death, according to a December 2023 study in the Journal of the American Heart Association³.

Diagnosis and treatment for EDS

If you think you’re dealing with EDS, Dr. Morse recommends keeping a symptom diary to record not only when and how long you sleep, but any other accompanying symptoms. This information can help your doctor and sleep specialists determine the root cause of your EDS.

“Sleep and wakefulness are intimately connected,” says Dr. Morse. “General medicine often dismisses sleep, and sleep medicine often dismisses when you’re awake. But the two are interconnected, and we need to know your symptoms to understand the impact during your awake hours and help us understand what’s going on.”

Along with sleep and symptom history, doctors will also use medical and medication history and, if appropriate, sleep testing, to help determine the cause of EDS, says Dr. Foldvary-Schaefer. How EDS is then treated will depend on what’s causing it, says Dr. Morse.

“Based on the condition causing EDS, treatment could include lifestyle changes, medications, or perhaps equipment,” such as CPAP machines for sleep apnea, says Morse. “It is really a unique treatment for everyone.”

When to seek help for EDS

Because conditions that cause EDS might take some time to diagnose and involve seeing specialists, don’t delay getting help, says Dr. Morse. If you’re dealing with EDS three or more days per week for at least three months, talk to your doctor about it, recommends Dr. Foldvary-Schaefer.

“It’s a call to action if a person is experiencing sleepiness chronically or episodically. Have a conversation with your doctor,” says Dr. Morse. “It’s important not to normalize sleepiness. It’s not normal, it’s just common.”

And, above all, don’t think EDS is something you can self-cure, says Dr. Morse. While keeping a consistent sleep routine could help with the occasional bout of fatigue, you may need more formal treatment for something like EDS (or disorders like narcolepsy, for example). “Don’t try to do it yourself,” she says. “EDS has immediate and long-term effects if not treated. See a doctor so you can find the root cause and find treatment that gives you acute and chronic relief.”

—reviewed by Angela Holliday-Bell, MD