Polysomnography Sleep Study – How Does it Work? [updated 2023]

polysomnography sleep study:

If you suspect you have a sleep disorder, then a polysomnography test can help determine what is keeping you from a good night’s rest.

This non-invasive and pain-free overnight sleep test is often used to identify underlying sleep issues and sleep disorders. If you’ve tried everything to find the perfect sleep solution but you’re still battling to get some shut-eye (and you don’t know why), a polysomnography test could give you the answers.

What does Polysomnography measure?

When we sleep, we go through 5 Sleep Cycle every 90 minutes. Polysomnography will analyse and measure your sleep behaviour during each sleep cycle. The test helps to investigate the causes and symptoms of sleep disorders such as:


This is a sleep illness where you feel sleepy throughout the day and may experience sudden sleep attacks and nod off at unexpected moments.

Sleep Apnea

You may experience abnormal patterns in breathing and gasp for air during sleep because of an obstruction in your airways.

REM Sleep Behaviour Disorder

In REM sleep, we become temporarily paralyzed so that we can’t act out our dreams. People who suffer from this disorder don’t go into paralysis and can physically react to their vivid and intense dreams.

Chronic Insomnia

There are two types of insomnia, chronic and short term. Chronic insomnia is characterized by having difficulty falling and staying asleep at night.

How does polysomnography work?

It might feel odd to sleep in front of strangers, but your sleep specialist will try to make the process feel as normal as possible. Think of it as a stay in a hotel room. Even personal items are allowed, like pajamas, so that you can sleep comfortably.

On the day of the sleep study, a technologist will place sensors on your scalp and body to monitor your heart rate, eye movements, breathing and brainwaves. The data taken during the polysomnography test will measure the time spent in each sleep stage, your waking patterns, how you breathe throughout your sleep, the position of your body and your brain’s activity.

Are sleep studies accurate?

A sleep study will give you the most detailed results because only data recorded during sleep is noted, making it very accurate. Sometimes people may prefer to use home tests to diagnose sleep apnea, for example, and these tests will record data from in between your sleep, making for inaccurate results. Sleep disorders are best diagnosed by polysomnography as the data will issue doctors with more information on your breathing rate, posture and sleep behaviour.

How to prepare for a sleep study?

On the day of the sleep study, avoid taking any stimulants of any kind as these can interfere with your sleeping patterns, so a cup of coffee is a no-go. Sedatives or muscle relaxants can interfere with the results of the test so you may have to stop taking them. If you’re accustomed to unwinding with a glass of wine, you might have to save that for the next day as you cannot consume alcohol before undergoing a sleep study.

What do the results show?

During your sleep, a polysomnography test will observe the following:

  • Brainwaves and eye movements
  • Heart and breathing rate changes and changes in blood oxygen
  • Frequent leg movements
  • Unusual movements or behaviours
  • Sounds made during sleep
  • Body posture while asleep

A technologist records your behaviour during each sleep cycle and takes note of your sleep quality. The data will help doctors to assess what sleep disorders or issues you may have.

Polysomnography tests help to diagnose sleep disorders that may be interfering with your quality of life. While you wait to take a sleep study test, it’s essential to get into a bedtime routine because not getting enough sleep can impact every aspect of your life like your health, career and relationships. Once you get the results of the sleep study, practicing good bedtime habits together with your doctor’s advice will set you up for sleep success.

Obstructive Sleep Apnea

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