Everyone can have difficulty sleeping now and then, but if lack of sleep is an ongoing problem, a sleep study, more formally called a polysomnography, might give you the answers you need to get a consistent good night’s rest.
“A sleep study allows us to diagnose sleep disorders by monitoring the sleep cycle and symptoms while the individual is asleep,” said Theodore Hubley, MD, a critical care physician who specializes in pulmonary disease and sleep medicine with the Froedtert & the Medical College of Wisconsin health network. “A sleep study will give us information about breathing, oxygen levels, heart rate, eye and leg movements and in some cases, brain activity.”
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Common Conditions Diagnosed with a Sleep Study
Sleep Apnea
Sleep apnea is the most common condition doctors diagnose using a sleep study. It is caused by pauses in breathing while a person is asleep. This can be due to narrowing of the airways during sleep, also known as obstructive sleep apnea. It can also be caused by a communication problem between the brain and the muscles used for breathing, which is called centralized sleep apnea. A sleep study can measure the duration of the pauses in breathing, how often a pause happens, how much effort it takes to breathe and if breathing is deep or shallow. Research published in 2025 by the National Sleep Foundation found 4 in 10 Americans have an elevated risk for sleep apnea, but many people go undiagnosed, untreated or both. The most common symptom of sleep apnea is loud snoring. The largest risk factor for sleep apnea is obesity. Atrial fibrillation (Afib), a cardiovascular condition that causes an irregular heart rate, has been associated with untreated obstructive sleep apnea. By seeking treatment for sleep apnea, people with this heart condition can significantly reduce their chances of having an irregular heart rate episode.
Narcolepsy
Narcolepsy is a disease of the central nervous system. This condition is characterized by excessive daytime sleepiness and causes people to suddenly and unexpectedly fall asleep. The exact cause of narcolepsy is unknown, but it is believed to be related to chemicals in the brain that help regulate sleep. A multiple sleep latency test (conducted during the daytime and after an overnight sleep test) can monitor brain activity and eye movement to help make a diagnosis. While there is no cure for narcolepsy, the disease can usually be managed with medication.
Sleepwalking
Sleepwalking is a condition in the parasomnia category that involves complex behaviors that occur during certain parts of the sleep cycle. People who are sleepwalking may appear awake, but they are not fully conscious, will lack coordination and will not have a memory of their sleepwalking episode. Episodes of sleepwalking could involve individuals acting out their dreams while still sleeping. Descriptions and video from loved ones can be compelling to help a doctor make a diagnosis, but a sleep study is ultimately used to confirm it.
Insomnia
Insomnia is a sleep disorder that can manifest as struggling to fall asleep or stay asleep. Insomnia is caused by many different factors, so it can be difficult to diagnose and treat. Often, a sleep study can help rule out other conditions that could be the cause. Insomnia has been associated with depression, anxiety and other health problems, including chronic conditions, such as a stroke, a heart attack, diabetes or high blood pressure.
Signs You May Need a Sleep Study
Talk to your doctor about a sleep test if you experience any of the following symptoms:
- Snoring that is loud and frequent
- Gasping or choking for air while sleeping
- Excessive daytime sleepiness
- Frequent urination at night
- Headaches that wake you up at night or in the morning
- Your sleeping partner says you flail your arms while you sleep or get out of bed while you are still sleeping
“At a patient’s first appointment, it can be very helpful to have their partner or spouse present, too,” Dr. Hubley said. “They may have information about the patient’s sleep habits that the individual cannot describe.”
Home Sleep Test vs. In-Clinic Sleep Study
If your doctor determines a sleep test/study is necessary, you may have the choice between an in-clinic sleep study and a home sleep test. People often prefer home sleep tests for convenience, but it is only appropriate for people with suspected obstructive sleep apnea. During a home sleep test, the patient is given the equipment that will measure heart rate, oxygen levels and breathing during sleep. The data is recorded onto a device that is returned to the doctor’s office for review.
An in-clinic sleep study happens at a sleep lab, usually between 8 p.m. and 6 a.m. This type of sleep test is appropriate for obstructive and centralized sleep apnea, narcolepsy, parasomnia disorders and certain types of seizure disorders. The in-clinic sleep study collects more data than a home sleep test, and a sleep technologist monitors the patient throughout the test. Breathing, brainwaves, muscle tone, eye movements, oxygen levels and other data are used to make a diagnosis.
“If sleep apnea is suspected, we can start treatment with a continuous positive airway pressure mask, or CPAP mask, during the sleep test,” Dr. Hubley said. “If the pauses in breathing stop when the mask is worn, we have a diagnosis and know what we need to do to treat it.”
A common concern for people who need an in-clinic sleep study is if they will be able to fall asleep. Sedation medication that has a minimal effect on the results of the test is available.
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