September 2020 | Reviewed by: Rafael Sepulveda, MD and Seema Khosla, MD
What is a sleep study?
A sleep study provides a sleep doctor with the most complete evaluation of your sleep. You will be required to stay overnight at a sleep center, hospital or a hotel room.
A sleep study, also known as polysomnography, records your brain waves, heartrate and breathing as you sleep. It also tracks your eye, leg and arm movements, and oxygen levels in your blood. This information will help your doctor make a diagnosis and develop a treatment plan.
Your medical provider or a sleep doctor may recommend a sleep study to:
- Test for sleep-related breathing disorders including sleep apnea
- Evaluate abnormal behaviors during sleep due to parasomnias
- As part of the evaluation of narcolepsy or other hypersomnia-related disorders
- Adjust the levels of airflow in patients who receive CPAP therapy for sleep-related breathing disorders
- Determine why treatment for a sleep disorder is not working
For some with suspected sleep apnea, their medical provider or sleep doctor may recommend a home sleep apnea test instead of a sleep study. A home sleep apnea test uses different equipment that you can set up yourself.
A sleep study is the way to ensure that you have the proper diagnosis for a sleep disorder. Speak with your health care provider if you think you might need a sleep study.
How to prepare for a sleep study?
A sleep study involves an overnight stay at a sleep center, hospital or even a special hotel room. These environments are set up to make you as comfortable as possible so you can have a full night’s sleep. Typically, you will not need to report for your sleep study until the early evening.
On the day of your sleep study, you should:
- Follow your regular routine as much as possible
- Avoid napping
- Avoid caffeine after lunch
- Avoid using hair sprays or gels that can interfere with the sleep recording
- Avoid alcohol or other sedatives unless otherwise prescribed by your doctor.
Your medical provider may recommend that you to temporarily discontinue using some medications prior to a sleep study.
When it is time to report for your sleep study, bring any items that you need for your nightly routine. Prepare for the sleep study as if you are staying at a hotel for a night. You may want to bring:
- Comfortable pajamas or clothes to sleep in
- A toothbrush, toothpaste and dental floss
- Makeup remover
- Reading material
- Clean clothes for the morning
When you arrive, a sleep technologist will ask about your sleep habits. There may be a questionnaire for you to fill out.
You will have some time to make yourself at home. There will not be any other patients in your room. You will have a bathroom and you may have a TV to watch.
What is the testing process for a sleep study?
After you arrive and have settled in, the sleep technologist will attach sensors to your body. The sensors, which are glued or taped to you, monitor your body while you sleep. These sensors are painless. Make sure to tell the technologist if you are allergic or sensitive to any adhesives. The sensors measure your:
- Brain waves
- Chin muscle activity
- Heartrate
- Breathing
- Oxygen levels
- Leg movements
The wires are long enough to let you move around and turn over in bed. At the start of the test, you will be asked to move your eyes, clench your teeth and move your legs. This will make sure that the sensors are working.
You are free to read or watch TV until your normal bedtime. When it is time for you to try to go to sleep, the lights will go off and a low-light video camera will allow the technologist to see you from a nearby room. If a sensor comes loose or you need to go to the bathroom during the night, the technologist will be there to help you with the wires.
Many patients do not sleep as well as they would at home. This may be because of the sensors or the unfamiliar environment. This typically does not affect the results. Nearly everyone falls asleep during a sleep study. In most cases, you do not need a full eight hours of sleep for the doctor to make a diagnosis. Occasionally, you may be prescribed medication to help you sleep during the study.
In the morning, the technologist will test and then remove the sensors. You may be asked to fill out a morning questionnaire that asks about the quality of your sleep and your experience in the sleep center. The study is complete once you are awake and the sensors have been removed.
How are sleep study test results scored?
Members of the sleep team will review and evaluate the information gathered during the sleep study. It may take up to two weeks to properly evaluate your sleep study.
A sleep technologist will first score your sleep study by marking your sleep stages and identifying any events of abnormal breathing or leg movement. The sleep doctor will then review the results to determine what kind of sleep problem you may have. After the doctor makes a diagnosis, the doctor that ordered the sleep study will contact you to discuss the results.