Sleep Study
Reviewed
Also called: Polysomnography, Sleep apnea study, Home sleep study
A sleep study, also known as polysomnography, is a test that measures and records different body functions while you sleep.
Specimen: N/A
Why this test may be ordered
- You have symptoms of a sleep disorder, such as loud snoring, gasping for breath during sleep, trouble falling or staying asleep, or excessive daytime sleepiness that may increase the risk of accidents.
- You have a known condition that can be affected by sleep disorders, such as depression, diabetes, or heart disease.
- Your provider wants to evaluate the severity of a suspected sleep disorder to guide treatment.
Preparation and collection
To prepare for your sleep study: Avoid alcohol and caffeine during the afternoon and evening before your test. Don't nap during the day. Don't use lotions, hair gels, or makeup before the test. Avoid using nail polish or artificial nails. If you normally take sleep medicines, talk to your provider about whether or not you should take the medicine before the test.
A sleep study is done during your normal sleeping hours. The study may be done at a hospital, a sleep study clinic, or in your own home. A home sleep study, also known as a sleep apnea study, is used to help diagnose sleep apnea. It does not diagnose other types of sleep disorders.
You may have some mild skin irritation from the electrodes. There are no other known risks to having a sleep study.
Understanding results
Your provider will review all the results and, if appropriate, provide a treatment plan.
- Apnea Hypopnea Index (AHI) above five episodes: This looks at how many episodes of sleep apnea happen in a night. If you have more than five episodes, it probably means you have sleep apnea. Limitation: You may not sleep as well during the sleep study, but a full night's sleep isn't necessary to get results. Next step: Your provider will review all the results and, if appropriate, provide a treatment plan.
- Oxygen below 90 percent during sleep: This measures the number of times your oxygen level drops during sleep. Lower than 90 percent oxygen is considered abnormal. Limitation: A home sleep study uses fewer sensors than a sleep study at a hospital or sleep clinic. But this test is not recommended if you have other sleep disorders or health conditions that could make your breathing more difficult. Next step: If you have questions about your results, talk to your provider.
- Home sleep studies use fewer sensors and are only used to diagnose obstructive sleep apnea; they are not recommended if you have other sleep disorders or health conditions that could affect breathing.
- You may not sleep as well during the study, but a full night's sleep is not necessary for results.
- In-lab studies involve a low-light video camera to record movements, which may raise privacy concerns for some individuals.
What to do next
If you have questions about your results, talk to your provider.
- What were my AHI (Apnea-Hypopnea Index) and sleep efficiency?
- How does my oxygen desaturation index (ODI) compare to normal?
- What do my results mean for my overall health and safety?
- Do I need further testing or a referral to a sleep specialist?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.