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EEG telemetry with sleep studies

Your child has been referred to the clinical neurophysiology department for sleep studies.

Your child may need 1 or both of these tests:

  • Video electroencephalograph (EEG) telemetry with polysomnography
  • Multiple sleep latency test (MSLT)

What is a video EEG telemetry with polysomnography?

This test can be needed for 2 reasons:

  • If your child is having unexplained symptoms during sleep
  • If they are sleepy during the daytime and the quality of their night time sleep needs to be looked at

Your child’s brain waves will be monitored using a video (EEG) as well as polysomnography. Polysomnography involves recording other signals such as eye movements, oxygen levels and body movements.


Please note, you and your child will be recorded on video in case your child has any symptoms that we need to re-examine. Video clips of any symptoms are kept as part of the record. All remaining video is deleted after the doctor has completed the report. We will ask you for your consent to do this. We may also ask permission to use the video for teaching purposes and you will be asked to give your consent separately for this.

Will they need to be admitted to hospital for this test?

Yes, your child will be admitted to a side room on Ward 1 or 3 at Sheffield Children’s hospital. They will not be able to leave the room for the duration of the test.

A telemetry recording is usually carried out over a period of 1 to 2 nights along with a simultaneous video recording. Your doctor will discuss the length of the admission best suited to your child.

How will this test help my child?

Recording over a longer period of overnight sleep increases the chance of capturing your child’s typical symptoms, if they are having any. This is important for us to make an accurate diagnosis and give the correct treatment.

This test will give us detailed information on the quality of your child’s sleep. We can monitor how much time is spent getting to sleep and once asleep, the time spent in different stages of sleep. We can also observe any changes in oxygen levels and heart rate as well as any disturbances caused by movements.

Is the test safe?

Yes, this test is safe and painless. It is records the electrical activity that your child produces naturally. If the doctors are trying to record any symptoms other than sleep, sometimes we may use activation techniques such as deep breathing or partial sleep deprivation. This involves putting your child to bed later and waking them up earlier than usual.

Occasionally the doctors may request a reduction in their usual medications. The associated risks of these techniques are discussed below.

Some children may have a minor skin irritation due to the products we use.

Is there anything we need to do before my child is admitted?

Yes, please make sure that you:

  • clean and dry your child’s hair and keep it free of any gel or styling products
  • continue to give your child their usual medications unless told otherwise by your hospital doctor. It is helpful to bring usual medications with you in original packets
  • bring them clothes and pyjamas that are button up where possible. This will make it easier when they are getting dressed and undressed
  • explain to your child what will happen and reassure them that they will be safe and cared for

Does someone need to stay with my child?

Yes, it is necessary for 1 parent or carer to stay with them throughout the whole stay. This is because they are in a room of their own and need to be supervised with the equipment. It is important that you identify when they are having their typical attacks.

If you need to leave for a short period, such as to collect lunch, then please inform the nursing staff.

What happens when we come into the hospital?

You will be in a single room with an en-suite bathroom.

There is a TV in the room and a DVD player and PlayStation may be available. Play workers on the ward will provide toys and art materials. You can also bring your own entertainment with you. You are allowed to use your mobile phone in the room and Wi-Fi is available.

Food is provided for your child but parents will need to use the restaurant facilities.

Please be aware the hospital is a smoke free site and this includes vape products.

What preparation is there for the test?

On the day of the test, 2 physiologists will visit you and your child to explain the test. You may ask any questions you have at this time. They will set up the equipment and make some measurements on your child’s head where the 23 discs need to be placed.

Illustration of child having their head measured Illustration of child having sticky paste put onto their forehead to connect to wires

Then with a cotton bud, we rub a small area with some abrasive paste. The discs are then applied using special glue. 2 stickers will be put on your child’s shoulders to record their heart rate. On some occasions other discs or stickers may need to be applied. This will vary and the physiologist will discuss this with you and your child before they are put on.

These extra discs may include:

  • discs placed above 1 eye, and 1 below the other eye to monitor eye movements
  • 2 stickers under the chin to monitor muscle tone
  • 2 stickers on each leg, just over the shin, to monitor limb movements
  • 1 sticker on 1 finger to monitor oxygen levels

Illustration of eeg test with stickers on child's head

Each sticker and disc has a wire plugged in to a small box that is connected to a computer by a long cable. This box can be carried on a belt around their waist or put in a backpack. This means your child can move freely around the room but remain in view of the video camera. Your child will not be able to have a bath whilst wearing the equipment but washing facilities are available.

What happens during the test?

The box records your child’s brain activity and you and your child will be recorded on video.

We will ask you to keep a note of their attacks and activities in a diary which we give to you. We also ask you to press a button if they have any symptoms.

If possible, it is important not to block the view of the video camera. This is so that we can study what happens in detail.

If an attack or any other event occurs during the night it is helpful to pull back the bedcovers so that we can see any movements.

The physiologist will visit to check the recording and discuss what has occurred. The nursing staff will be available to help with any problems.

Illustration of child on bed with recorder over their shoulder and button in hand

What else might the doctor want to know?

If the doctor also wants to capture any other symptoms or attacks your child is having, we may perform 1 or more of the following activation procedures.


This is taking deep breaths in and out, like blowing a candle out. In the case of young children we do this using a party blower or a windmill.

They may feel dizzy or get pins and needles whilst doing this. These are normal side-effects and will go away when they have stopped taking the deep breaths. We will ask about any health problems they have which would make the deep breathing unsafe. The deep breathing causes a change in blood flow which may change their brain waves and give extra information to help make a diagnosis.

Illustration of child blowing on a party blower with sticky wires connected to their head

Risks of hyperventilation

Hyperventilation (deep breathing) is associated with a risk of triggering:

  • a clinical event which affects less than 3 percent of patients
  • a seizure which affects 2 percent of patients
  • a generalised tonic-clonic seizure which affects 0.03 percent of patients

You will be asked to give consent to this part of the test. There is no alternative way to get the information obtained during hyperventilation.

Photic stimulation

A lamp which flashes on and off at different speeds will be placed in front of your child. They will be asked to look at it.

In a small percentage of children, the flashing light could trigger a seizure (this is called photosensitivity). If your child has this response the light is turned off quickly and they would not usually go on to have a seizure.

Illustration of child looking at images flashing in front of them with sticky wires connected to their head

Risks of photic stimulation

The risks of photic stimulation are that your child may have:

  • a clinical event which affects less than 2 percent of patients
  • a seizure which affects 0.7 percent of patients
  • a generalised tonic-clonic seizure which affects 0.07 percent of patients

The information from photic stimulation may lead to a definite diagnosis and help the consultant to decide on treatment. You will be asked to give your consent to the procedure and there is no alternative way to get this information.

Drug reduction

In some cases a drug reduction may be used after talking with your doctor to increase the chance of capturing your child’s typical attack. You will be asked to consent to this happening and you should ask the doctor for any information on the risks associated with drug reduction.


Drug reduction may lead to an increase in the frequency or severity of episodes and this would be managed by the doctors looking after your child on the ward.

We must have your consent for any procedure or treatment beforehand. Staff will explain all the risks, benefits and alternatives before they ask for your consent. If you are not sure about any aspect of the procedure or treatment proposed, please ask for more information.

What happens after the test?

If your child is not having a multiple sleep latency test (MSLT), then the test will have finished and the electrodes will be removed using a solution to dissolve the glue.

A small amount of the glue will left in their hair. This will come out after they have had their hair washed and conditioned a few times. If you have an old hat which you do not mind getting some of this solution on, you may wish to bring it for the journey home.

If your child is having a multiple sleep latency test (MSLT) this will be performed on the following day, starting in the morning.

What is a multiple sleep latency test?

A multiple sleep latency test (MSLT) is a test which your child is given 4 or 5 opportunities to sleep in a quiet darkened room whilst having their brainwaves monitored. The test measures the average time for a person to fall asleep.

How will having a multiple sleep latency test help my child?

The average time it takes to fall asleep is a measure of daytime sleepiness. Knowing this may help to distinguish tiredness from excessive daytime sleepiness and can also help to investigate narcolepsy. Narcolepsy is a disturbance in the wake and sleep regulating system, 1 of the common symptoms is excessive daytime sleepiness.

Where is the MSLT test done?

Your child will stay in the room where the EEG video telemetry with polysomnography is taking place.

Is there anything my child needs to do before having the MSLT test?

Some medications will need to be stopped before the test. Your doctor will advise you if this is necessary for your child. From midnight the night before the MSLT test your child should not have anything that contains caffeine. Caffeinated products include:

  • coca-cola
  • chocolate
  • tea and coffee

Your child will need to stay awake between naps.

Please remember that any food or drinks your child consumes throughout the day should still not contain caffeine.

How long will the MSLT test take?

This procedure is time consuming. On the day of the test you and your child will need to remain available on the ward from 8.30am until around 6pm. On some occasions it may end earlier at around 4pm.

What happens on the day of the test?

On the morning of the test, the physiologist will come to the ward to get your child ready for the MSLT. Some discs and stickers will be removed to make your child more comfortable. All of the contacts on your child’s head will be left in place.

At 9am your child will be settled and left undisturbed to sleep for around 30 minutes with the lights turned off. Your child will then be woken and the test will be repeated every 2 hours at 11am, 1pm, 3pm and 5pm. In between these times it is necessary for your child to stay awake.

What happens after the test?

When the test is complete the electrodes are removed using an oily solution to dissolve the glue. A small amount of the glue is left in their hair. This will come out after they have had their hair washed and conditioned a few times. If you have an old hat which you do not mind getting oil on, you may wish to bring it for the journey home.

When will I get the results?

You will not get the results of the test during your stay as a large amount of information needs to be interpreted. Once this has been done, the results will be sent to your child’s hospital consultant within 3 weeks. Before you are discharged from the ward we will arrange a future time to discuss the results.

We will always ask for your consent before for any procedure takes place. Staff will explain all the risks benefits and alternatives before they ask for your consent.
If you are unsure about any aspect of the procedure proposed, please do not hesitate to ask for more information.

Contact us

If you have any questions or concerns please ring the department of clinical neurophysiology Monday to Friday between 8.30am and 4.30pm on 0114 271 2526.

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Please note: this is a generic information sheet relating to care at Sheffield Children’s NHS FT. These details may not reflect treatment at other hospitals. This information is not intended as a substitute for professional medical care. Always follow your healthcare professionals’ instructions. If this resource relates to medicines, please read it alongside the medicine manufacturer’s patient information leaflet. If this information has been translated into another language from English, efforts have been made to maintain accuracy, but there may still be some translation errors. If you are unsure about any of the guidance in this resource or have specific questions about how it relates to your child, always ask your healthcare professional for further advice.

Resource number: NPS10

Resource Type: Article

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