A sleep study – also called polysomnography - is the most common diagnostic test for obstructive sleep apnea (OSA).¹

The process involves an overnight stay at a hospital or sleep clinic while specialists monitor your breathing, heart rate, and other body systems while you sleep. While an in-lab study is the most comprehensive way to assess sleep quality, at-home sleep studies are also used as a diagnostic tool. 

While a sleep study may be intensive, it can be worth the disruption. Sleep apnea is a serious disorder that can have an ongoing impact on your health, causing issues like chronic sleep deprivation, heart disease, depression, diabetes, and problems with immunity.² Without a sleep study, it’s difficult to diagnose and treat the issue.

In this article, we explain why you may need a sleep study and what to expect from the process.  

What is a sleep study? 

A sleep study is a comprehensive look at the way your body systems behave during sleep. By measuring your breathing, heart rate, blood oxygen, blood pressure, body movements, and brainwaves, specialists can identify signs of sleep apnea. 

At-home sleep test  

Instead of sleeping at a clinic or hospital, this test is taken at home using a self-testing kit. Body systems are measured overnight, and results are then shared with your specialist so they can make a diagnosis. 

Preparing for a sleep study  

When you book a sleep study, you’ll be given instructions on how to prepare. 

Preparations could include:¹  

• Avoiding caffeine and alcohol in the days leading up to the study. 
• Not taking your regular medication on the day of the test (if advised by your medical practitioner). 
• Bringing comfortable clothing to sleep in and your usual pillow. 
• Bringing a book or magazine to help you get to sleep.  

What is measured during a sleep study? 

During an in-lab sleep study, doctors and/or other specialists in the sleep team track a wide range of your body systems, including breathing, heart rate, blood pressure, blood oxygen, and body movements. 

Tests include: 

EEG (electroencephalography) 
 Using small sticker-like sensors attached to your face and head, your team will measure and record your brain waves to establish which of the sleep cycle phases you are in, as you sleep. 

EMG (electromyography) 
 Electromyography records muscle activity through the body, including teeth grinding, face twitching, and leg movements, using sensors attached at different points. These movements are used to identify the REM (rapid eye movement) sleep stage. 

EOG (electrooculography) 
 This test tracks eye movements with a sensor attached near the eyes. These are used to help identify sleep stages, including REM and deep sleep. 

EKG (electrocardiography) 
 Electrocardiography sensors attached to your chest measure your heart rate and rhythm, track changes over time, and identify unusual patterns (arrhythmia). 

Nasal airflow test 
 Using a pair of small tubes, or cannulas, that sit inside the nostrils, this test records breathing patterns during sleep.  

Snore microphone test 
 A tiny microphone attached to your clothing records snore rates and volume. 

Pulse oximeter 
 A small clip worn on the end of your finger tracks fluctuations in blood and skin oxygen levels.  

Concerned about sleep apnea? 

OSA, the most common sleep apnea, can be a dangerous condition with a raft of potential implications for your health and well-being if left untreated. It’s important to take action if you notice symptoms. Go to What are the symptoms of sleep apnea? 

Frequently asked questions 

How do I know if I need a sleep study? 

Your medical provider will generally recommend a sleep study if you have multiple symptoms of sleep apnea. These include loud snoring, difficulty staying asleep (insomnia), frequent daytime tiredness (hypersomnia), problems with focus, headaches or dry mouth in the mornings and gasping or choking awake during the night. Talk to your doctor if you’re concerned about your symptoms. Take the F&P Healthcare sleep assessment quiz.

Is anyone in the room during a sleep study? 

A sleep study involves spending one or more nights sleeping in a hospital or specialist clinic. Medical staff will attach monitors and testing sensors when you arrive, then leave you to sleep alone – nobody will be in the room while you sleep. In some cases, video and/or audio monitoring may be used to check snoring or breathing patterns, but your medical team will let you know if this is happening.   

How long does a sleep study take? 

Generally, a sleep study takes place over a single night of sleep. You will be asked to come to the clinic early in the evening and sleep until the following morning. In some cases, further testing may be needed to confirm your results. 

The content is for educational purposes only. It should not be used as a substitute for the medical advice of one’s healthcare provider.