Polysomnography Sleep Test

Polysomnography Sleep Test

Polysomnography (PSG) is a special type of sleep test which provides the most detailed information about breathing problems during sleep.

Copyright: KidsHealth

A boy ready for a sleep study


Key points about polysomnography

  • polysomnography (PSG) is a special type of sleep test which provides the most detailed information about breathing problems during sleep
  • it involves attaching small sticky sensors to your child's head, face, chest and legs
  • your child will usually need to sleep the night with the sensors on, either on a hospital ward or special sleep unit
  • a video and sound recording of your child's sleep will usually happen at the same time
  • you stay with your child for the whole time - both to support your child and help staff keep the sensors in place

Why might my child need a sleep test?

Sometimes no test is needed

Sometimes, the information that you tell your doctor about your child's sleep and snoring is very straightforward. They can easily make a diagnosis. Your child won't need any tests to decide on their treatment.

Sometimes a test at home is helpful

Some children might need a test that can happen at home. An example of this is an overnight oximetry test that measures oxygen levels during sleep.

Find out more about overnight oximetry

Some children need a detailed sleep test (polysomnography or PSG)

For some children, there is a need for more detailed information about their breathing and body movements during sleep. These children might need polysomnography (PSG).

What is polysomnography?

PSG is a special type of sleep test which provides the most detailed information about breathing problems during sleep.

PSG records the following during sleep:

  • breathing patterns
  • oxygen levels
  • brainwave activity
  • eye movements
  • body movements

PSG is used to investigate problems like:

  • obstructive sleep apnoea (OSA)
  • daytime sleepiness
  • unexplained waking overnight

Find out about snoring or noisy breathing and OSA

What happens during polysomnography?

PSG setup and attaching the sensors

The setup for PSG will begin before your child's bedtime and can take up to 1 to 2 hours. Your child will usually get into their pyjamas first and sit on a chair or lie on the bed. A member of the healthcare team will put on the sensors. While this is happening your child can read or do a quiet activity like colouring in or watching a video.

Around 20 small sensors are attached to your child's head, face, chest and legs. These sensors stick to the skin and connect to monitors by thin wires. A sensor at the nose measures whether there are any pauses in your child's breathing. Soft bands around your child's chest and tummy measure how hard your child is trying to breathe.

A video and sound recording while your child sleeps

Your child will usually need to sleep one night with the sensors in place. This is either on a hospital ward or special sleep unit. A video recording of your child's sleep will usually happen at the same time. The video and microphone are focused on the bed your child is sleeping in. It will also record your activity and noises in the room. It's helpful to keep quiet and avoid loud noises so there is a good recording of your child's noisy breathing.

Your sleep healthcare team may need to come into the room during the night to attach any sensors that have come off.

Making it as comfortable as possible for your child

While having a PSG doesn't hurt, some children find the sensors irritating and young children may find it difficult to accept some of the sensors. The healthcare team will work to make the test as comfortable as possible for your child.  

The next morning

Your sleep healthcare team will remove the sensors after your child has woken the next day.

Sometimes doctors will ask for a finger prick blood test the next morning. 

How can I help prepare my child for polysomnography?

Make sure your child is well

Please make sure your child is well enough for the sleep test to go ahead. If your child is unwell, you may need to make another time for your child's sleep test. Please contact the healthcare team as soon as possible. 

Explain what will happen

You can help prepare your child by explaining what is going to happen and reassuring them that you will stay with them while they have the test. 

Keep up normal daytime naps

Young children should have their normal daytime naps on the day of the PSG. This stops them being overtired. 

Take some of your child's favourite things to the appointment

It is helpful if you can take something with you for your child to do while the sensors are being put on. This could be a favourite toy, book, colouring in or tablet activity. Taking their own pyjamas, a favourite pillow or blanket may make your child feel more relaxed when sleeping in a strange place. 

Avoid using creams on your child

Please avoid using creams or other products on your child's hair or skin on the day.

Spend the night with your child

You will spend the night with your child, so that your child has the best possible sleep and doctors can get the most information from the test. 

Take any other things you need to the appointment

If your child needs any medicines or feeds overnight, please take them with you to the appointment.  

If your child is using any breathing support (such as CPAP) please take the machine and mask with you. 

Are there any risks from polysomnography?

There is little risk involved. Very occasionally a child's skin may react to the tapes or sensors resulting in a short-term rash. 

PSG itself is painless but may be uncomfortable and sometimes your child needs a blood test in the morning as part of the assessment. 

What will happen after the polysomnography?

Most children and babies have a near normal amount of sleep during the test and can go home early in the morning and continue normal activities.

PSG provides a great deal of information about sleep and breathing and takes several hours to fully analyse. You may receive some initial results the same day, but it may be a week or two before the study is fully analysed and reported. 

Your doctor will arrange follow-up based on the results of the PSG.

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This page last reviewed 29 August 2022.

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