Sleep Study

A sleep study, also called a polysomnogram or PSG, helps your doctor work out if you have a sleep disorder.

What is a sleep study?
Why do I need a sleep study?
What are the risks of a having a sleep study?
How do I prepare for a sleep study?
What happens during a sleep study?
What happens after a sleep study?

What is a sleep study?

A sleep study is a non-invasive, specialised test that monitors many of your body’s physiological processes while you’re sleeping. Small adhesive sensors are applied to the surface of your scalp, face, chest, fingers and legs to measure:

  • Airflow at your nose and mouth
  • Body position
  • Chest and abdominal wall movement during breathing
  • Electrocardiogram (ECG – heart rate and rhythm)
  • Electroencephalogram (EEG – brain waves)
  • Electromyogram (EMG – muscle tone)
  • Electro-occulogram (EOG – eye movements)
  • Leg movements
  • Oximetry – (blood oxygen level)
  • Snoring and sound.

A sleep study helps your doctor diagnose a range of disorders associated with sleep. The data collected during your sleep study provides information about the quality of your sleep based on:

  • Different REM (Rapid Eye Movement) and non-REM stages of sleep you entered
  • Sleeping patterns
  • The number of arousals from sleep you may have had as a result of a sleep disorder
  • The type and severity of any sleep disorder identified during the study.

Find out more about sleep disorders

The table below outlines the different types of sleep studies.

Name of sleep study

 What does it measure?

 When is it used?

Diagnostic Sleep Study.

Read our Sleep Study Information Sheet.

The body’s activities during sleep.

To detect snoring, obstructive sleep apnoea, or periodic limb movement disorder, cause for insomnia, excessive daytime sleepiness.

Therapy Sleep Study.

Read our Sleep Study Information Sheet.

Compares the body’s activities during sleep whilst having treatment or therapy.

To ensure the therapy has a desired improvement.

CPAP Titration Study.

Read our CPAP Titration Information Sheet.

The level of air pressure required to control snoring and sleep apnoea.

For people with Obstructive Sleep Apnoea to determine the optimal CPAP setting.

BPAP Titration Study.

The level of air pressure required to control sleep apnoea and hypoventilation.

For people with Central Sleep Apnoea to determine the optimal BPAP setting.

Multiple Sleep Latency Test (MSLT).

Read our MSLT Information Sheet.

Brain waves, eye movements, muscle activity and heart rhythm during sleep.

Immediately following an overnight sleep study to measure how often and how quickly people fall asleep during nap periods in the day.

Maintenance of Wakefulness Test (MWT).

Read our MWT Information Sheet.

Sleep stages and the ability to stay awake during the day – measuring brain waves, eye movements and muscle tone.

To assess treatment or therapy for a sleep disorder, driving or occupational safety.

Why do I need a sleep study?

Your doctor may recommend you have a sleep study if they suspect you have a sleep disorder. Sleep disorders include having difficulty falling asleep or staying asleep.

Some disorders cause your sleep pattern to be disturbed or disrupted. This means you never reach the deep level of sleep that allows you to feel refreshed and well rested in the morning. As a result, you may notice the following daytime symptoms:

  • Difficulty staying awake when sitting still, watching TV or reading
  • Falling asleep, or feeling very tired, while driving
  • Feeling irritable and have trouble controlling your emotions
  • Feeling like you must take a nap almost every day
  • Feeling sleepy during the day
  • Having difficulty concentrating and performing mental tasks
  • Having difficulty remembering things
  • Requiring caffeinated beverages to keep going
  • Waking with a headache.

Many people are unaware they have a sleep problem. Often, it’s your bed partner or a family member who first notices a potential problem.

What are the risks of a having a sleep study?

A sleep study is a non-invasive and pain free procedure with virtually no risks. You may feel slight discomfort as a result of the numerous leads applied to your face and body. You may also experience mild skin irritation due to the sensor and tape adhesive; this generally subsides once the sensors are removed.

How do I prepare for a sleep study?

There is no special preparation for a sleep study. A sleep study aims to mimic a typical night’s sleep at home.

On the day of the test, try to:

  • Avoid caffeine and energy drinks (in the evening of the study)
  • Avoid napping
  • Consume your usual quantity of alcohol
  • Don’t apply make-up, oils, gels or lotions to your skin, as these can interfere with the sensors
  • Follow your usual routine
  • Have a shower, making sure your skin and scalp are clean and dry
  • Take your medications as usual.

What happens during a sleep study?

A sleep study can be performed during an overnight stay in hospital. Or, the study can be performed at home using a portable sleep monitoring system.

If your study is performed in hospital, you will sleep in a private bedroom with an adjoining ensuite. The room is dark and comfortable for sleeping. A Sleep Technologist will stay with you all night to monitor the sleep recording from a nearby room and provide assistance if needed.

Arriving for your study

You’ll be asked to arrive several hours before bedtime, to allow you time to settle and get ready for bed. The Sleep Technologist will apply the sensors using a mild adhesive paste or tape. The sensors are connected by wires to a computer that records your data but are long enough to let you turn and move around in bed. The set-up for your sleep study takes around 45 minutes. When the sensors are applied, you can still move around your room, read or watch TV until you are ready to go to bed.

During the night

Your comfort and safety during the test are very important. Your room has a low-light video camera so the Sleep Technologist can see what’s happening in the room when the lights are out. There is also an intercom system so you can communicate with the technologist during the night. You will be wearing several sensors, but as they connect to a single box they can be quickly disconnected if you need to get up during the night or go to the toilet.

Many people wonder how they’ll be able to sleep in a different environment wearing monitoring equipment. Surprisingly, most people sleep well. You may find it takes you a little longer to fall asleep than usual. Also, you may not sleep as well as you do at home; however, this usually doesn’t affect the test results. A full night’s sleep isn’t required to obtain useful information from your study.

In the morning

The Sleep Technologist will wake you and remove the sensors. You may wish to shower before leaving, as the adhesive paste (used to attach the sensors to your scalp) can only be fully removed with soap and water. A light breakfast is provided before you leave. You can return to your usual activities following the test.

Home sleep study

Some patients prefer the sleep study at home rather than in the hospital. If your doctor agrees, the Sleep Unit will provide you with a portable sleep monitoring system that you can take home. The Sleep Technologist will show you how to apply and connect the various sensors to the portable device, so you can operate the system. You will also be given written instructions.  After completing the study overnight, you’ll need to return the system to the hospital the following day so your data can be downloaded and analysed.

What happens after a sleep study?

After your sleep study, make an appointment with your doctor to discuss your results. Your doctor will help you determine next steps including any treatments or therapies. If left untreated, many sleep disorders can lead to excessive daytime sleepiness, impaired mental function (lack of concentration, poor memory), decreased performance at work, and greater possibility of accidents while driving.

Untreated breathing disorders associated with sleep may also increase your risk for heart problems, high blood pressure, and stroke.