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What to expect during a sleep study

Learn what happens during a diagnostic sleep study and how doctors use it to diagnose sleep disorders.

September 24, 2026 | 5-minute read

In this article

What is a sleep study and how does it work?

A sleep study is a painless overnight test that monitors your body while you sleep. It helps doctors evaluate your sleep and identify conditions that may affect your sleep and overall health. During a sleep study, sensors record information such as:

  • Brain activity
  • Breathing patterns
  • Heart rate
  • Oxygen levels
  • Body movements

Types of sleep studies

Different types of sleep studies may be used based on your symptoms and sleep concerns.

  • Polysomnography (PSG): An overnight sleep study completed in a sleep lab.
  • Home sleep test (HST): An overnight sleep study completed at home using equipment and instructions provided by the sleep lab.
  • Multiple sleep latency test (MSLT): A daytime test used to measure how quickly you fall asleep. 
  • Maintenance of wakefulness test (MWT): A daytime test used to measure how well you stay awake.
  • CPAP titration study: An overnight sleep study used to determine the CPAP settings needed to treat sleep apnea. 
  • Split-night sleep study: An overnight study that combines sleep apnea testing with CPAP titration during the same night. 

The results can help doctors diagnose obstructive sleep apnea (OSA) and other sleep disorders and recommend the right treatment.

Why might I need a sleep study?

Your doctor may recommend a sleep study if you have symptoms that suggest a sleep disorder.

Common symptoms include:

  • Loud snoring
  • Waking up gasping for air
  • Excessive daytime sleepiness
  • Trouble falling or staying asleep
  • Pauses in breathing during sleep

A sleep study can help diagnose conditions such as sleep apnea, narcolepsy, restless legs syndrome and other sleep-related disorders.  

How do I prepare for a sleep study?

Your care team will provide instructions before your appointment. To prepare for your sleep study, you may be asked to:

  • Avoid caffeine, alcohol and nicotine before the study
  • Skip daytime naps
  • Avoid lotions, makeup and hair products that could interfere with the sensors
  • Bring comfortable sleepwear
  • Bring items you normally use as part of your usual bedtime routine.
  • Ask your doctor whether you should take your usual medications before the study

Sleep studies are generally safe and painless. Some people experience mild skin irritation where sensors are attached, but this usually goes away shortly after the test is complete.  

What happens during a sleep study?

Most sleep studies take place overnight in a sleep center. After you arrive, you'll have time to get comfortable and change into your sleepwear before the study begins. 

A sleep technologist will place sensors on areas such as your scalp, face, chest and legs. The sensors are painless and connected to equipment that records information while you sleep.

Before bedtime, the technologist may ask you to blink, move your legs or clench your teeth to make sure the equipment is working properly. Once everything is set up, you can settle in and sleep as normally as possible.

Throughout the night, trained specialists monitor you and the equipment from another room using audio and video technology.

What does a sleep study show?

During a sleep study, sensors are used to track what happens in your body while you sleep. This information helps doctors understand your sleep patterns and identify possible sleep disorders.

The sleep study sensors may measure:

  • Brain activity (EEG): Helps identify different stages of sleep and monitors brain waves
  • Heart rate and rhythm (EKG or ECG): Records how your heart functions during sleep
  • Breathing patterns and airflow: Tracks breathing effort and airflow throughout the night
  • Blood oxygen levels (pulse oximetry): Measures oxygen levels in your blood while you sleep
  • Eye movements: Helps identify different stages of sleep
  • Muscle activity and tone (EMG): Records muscle movement in the arms and legs that may affect sleep quality

These measurements help doctors diagnose sleep disorders and recommend treatment.  

What happens after a sleep study?

The morning after your sleep test, the sensors are removed and you can usually return to your normal activities. Sleep specialists review the information collected during the study and analyze the results.

Your doctor will discuss the results with you and explain any recommended next steps. Depending on the findings, treatment may include lifestyle changes, additional testing or therapies designed to improve your sleep.

Good sleep plays an important role in your overall well-being. Learn more about healthy sleep habits and the benefits of quality sleep.

Other common questions about sleep studies

  

Sleep labs are designed to be comfortable, quiet and welcoming. Sleep study rooms often feel similar to a hotel room and are set up to support a restful overnight stay. Even if you don't sleep exactly as you would at home, doctors can usually gather enough information to evaluate your sleep.

If you're experiencing sleep disorder symptoms, start by talking with your primary care doctor. They can review your symptoms, health history and sleep concerns to determine whether a sleep study may be appropriate.

Depending on your needs, your doctor may refer you to a sleep specialist for additional evaluation, testing or treatment recommendations.

An in-lab sleep study, called PSG Test, takes place overnight in a sleep lab and monitors multiple body functions while you sleep. 

A home sleep test (HST) is completed at home using portable equipment that focuses primarily on breathing and oxygen levels. Your doctor will determine which test is right for you.

It's common to worry about not sleeping during a sleep study. Even if you sleep less than usual, doctors can often collect enough information to evaluate your sleep and identify potential sleep disorders.

Follow your doctor's instructions about medications before your sleep study. Be sure to ask whether you should take your usual medications or avoid any medications that could affect test results.

During a polysomnogram, sensors may be placed on your scalp, face, chest, legs and finger. These sensors monitor brain activity, heart rate, breathing patterns, oxygen levels, eye movements and muscle activity while you sleep. They help doctors gather information needed to diagnose sleep disorders and recommend treatment.

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  • National Heart, Lung, and Blood Institute. Sleep studies. Updated March 24, 2022.
  • MedlinePlus. Sleep study. Updated September 16, 2024.
  • American Academy of Sleep Medicine. Sleep study. Reviewed September 2020.

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