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Diagnosing a sleep disorder

If you're not sleeping well, talk to your doctor. He or she can use a variety of tests to find out why.

Everyone has a bad night's sleep now and then. But for some people, a night of restful slumber is a rare occurrence.

If you're one of them, it's important to get help. Without treatment, ongoing sleep trouble can increase the risk of high blood pressure, heart attack, stroke and other health problems, according to the National Heart, Lung, and Blood Institute (NHLBI).

Fortunately, your doctor has a number of diagnostic tools available to help find out what's causing your sleep trouble. (To get an idea of whether you might need to see a doctor, take this short Sleep Assessment Quiz.)

The first steps

To start with, your doctor will likely ask questions about your sleeping habits, such as:

  • How often do you have trouble sleeping?
  • What's your bedtime routine?
  • How long does it take for you to get to sleep?
  • Do you wake up during the night? How often?
  • Do people say you snore or gasp for breath while you sleep?
  • Do you feel tired or doze off during the day?

Your doctor may ask you to keep a sleep diary for a week or two to record specific sleep issues. You may be asked to note how much sleep you get each night, how sleepy you feel during the day and the number of naps you take, among other things.

Your doctor is also likely to review your medical and family history—ongoing health problems, medications and stress can all play a role in how you sleep. A physical exam and blood test also may be needed.

How a sleep study might help

Your doctor might also recommend that you undergo a sleep study. These painless, noninvasive tests are done at a sleep center, which may be part of a hospital or a stand-alone facility.

Some tests are done overnight; others during the day. In general, the tests use small sensors attached to your head and body to record your brain activity, eye movements, heart rate, blood pressure, the amount of oxygen in your blood and other relevant factors.

Types of sleep studies include:

Polysomnography (PSG). This test can help diagnose narcolepsy and certain sleep-related seizure disorders. It is also the most common and accurate test to detect obstructive sleep apnea, a nighttime breathing disorder in which a person's airway becomes blocked during sleep.

The test uses sensors to measure how you breathe during sleep. If readings taken during the first several hours of the test point to sleep apnea, the rest of the night is used to properly fit you with a home breathing aid known as a continuous positive airway pressure (CPAP) machine.

A CPAP machine keeps your airway open by delivering gently pressurized air to the back of the throat through a nasal mask. It's the most common sleep apnea treatment.

Multiple sleep latency test (MSLT). This is a daytime test typically done the morning following a PSG to help your doctor diagnose narcolepsy, according to the American Academy of Sleep Medicine. It measures how sleepy you are during the day.

During the test, you lie quietly in bed and try to go to sleep. Sensors on your head and face show when you’re asleep or awake. The test is repeated four or five times with two-hour breaks in between.

Maintenance of wakefulness test (MWT). This is also a daytime test usually done after a PSG. It measures your ability to stay alert during the day.

If you're being treated for a sleep disorder, one or more MWTs can help gauge the treatment's effectiveness. The test can also help determine if you're able to drive or perform job-related tasks without becoming drowsy.

For this test, you sit in bed and try to stay awake as long as you can while sensors record your responses. There are usually four 40-minute testing periods with a two-hour break in between.

The next steps

With the results of your sleep study tests, physical exam and medical history, your doctor will determine the cause of your sleep problem and develop a treatment plan.

To learn more about sleep disorders, visit the Sleep health topic center.

Reviewed 12/21/2022

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This information is provided for educational purposes only. Individuals should always consult with their healthcare providers regarding medical care or treatment, as recommendations, services or resources are not a substitute for the advice or recommendation of an individual's physician or healthcare provider. Services or treatment options may not be covered under an individual's particular health plan.