What is a sleep study?
Poly means ‘many’, somno means ‘sleep’ and graphy refers to ‘recording’. During a sleep study or polysomnography, several of your child’s bodily functions are measured during sleep:
- brain activity
- breathing (and possibly snoring)
- heart rate
- oxygen saturation
- CO₂ (carbon dioxide)
- muscle activity/eye movements
A video and sound recording are also made to provide a full picture of your child’s nighttime activity.
Preparing for the examination
To the hospital
Arrive on time at the sleep centre. Allow at least 30 minutes before your appointment to park, register, and report to the ward.
- You should come in the morning if your child uses a ventilation device (so the device can be technically checked).
- You should come in the afternoon for diagnostic examinations.
This allows the child to get used to the new environment, the room, and the technical setup.
What should you bring?
- Kids-ID
- Child’s nightwear: pyjamas or a bodysuit with press studs
- Socks, own blanket, possibly a night light
- Medication, nappy cream, possibly nappies
- Toiletries, shampoo, brush or comb
- Cuddly toy, dummy, toys, music box...
- Papers for the hospitalisation insurance or the parents’ employer
- Optional: ventilation or CPAP device the child is already using.
What does the room look like?
The room is spacious and has a bathroom with shower. There is also a TV, radio, and free wifi.
An extra folding bed is provided for the rooming-in person.
Food and drink
Dinner for the children is served between 17:30 and 18:00; breakfast is provided in the morning. Please note: only breakfast is provided for parents or carers.
Special food for the child can be ordered in advance by phone (bottle feeding, fruit puree, tube feeding, etc.).
Water, coffee, and tea are available on the ward.
Overnight stay of the parent
Children may feel anxious or uncomfortable in a new environment, especially if they have to sleep there. We therefore recommend that a parent (or other trusted person) be present from the beginning of the admission until the morning after the study. The parent or trusted person can stay overnight (rooming-in) on an extra folding bed in the child’s room.
If the child is physically or mentally younger than 12 years, rooming-in is mandatory.
Only breakfast is provided for the rooming-in person. For lunch, dinner, or other snacks, you can go to the visitors’ restaurant, the take-out, or the various vending machines in the hospital.
Switch off your mobile phone
Turn off your mobile phone and disconnect all other internet connections during the sleep study. They may interfere with the measurements.
Course of the examination
After the doctor and nurse have come by for a medical check-up, we put on the sleepwear and all the sensors are placed for the night.
What do we measure and how?
- We use two breathing bands, one around the chest and one around the abdomen, to measure breathing.
- We apply 15 electrodes to the chest, face and head. This is done using a white paste and hypoallergenic adhesive pads, and it does not hurt.
- Two electrodes on the chest to monitor heart rate (ECG)
- One electrode in the middle of the forehead
- Two electrodes next to the eyes to measure eye movements
- Two electrodes on the chin to measure muscle activity (EMG)
- Six electrodes on the skull and two behind the ear to measure brain activity (EEG)
- All the electrodes are bundled together at the back of the head and held in place with a stretchable net.
- The electrodes are connected to a measuring device that can be carried in a small backpack or installed in the bed.
- Finally, we place a small microphone near the throat to record breathing or snoring sounds.
Bedtime
The sleep recording begins when the child goes to bed and lasts at least 8 hours. This is a legal requirement for the reimbursement of the study.
Before bedtime, we place the final sensors:
- an oxygen sensor on a finger or toe
- ankle bands with sensors to measure leg movements (from age 6)
- a nasal cannula with sensors to measure breathing through nose and mouth
- a sensor on the chest to measure CO₂
Why all these sensors?
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Sensors can be uncomfortable for the child, but they are essential to assess possible causes of disturbed sleep. Proper attachment of the sensors is therefore very important. This enables us to make the most accurate diagnosis and offer the child the best possible treatment.
Once the signals are checked to ensure good-quality measurements, the device is connected to the polysomnograph via a long cable. This device records all signals and is connected to the computers in the analysis room.
What if the child sleeps with a ventilation or CPAP device?
The device is connected to the polysomnograph. During the study, possible issues with ventilation (leakage, pressure too high or too low…) can be detected. After analysing the sleep study, the doctor can make the appropriate adjustments to the device.
The morning after the examination
Once the child is awake and the measurements have been recorded for at least 8 hours, they may get up.
All electrodes are removed painlessly. The electrodes in the hair can easily be rinsed out in the shower.
After breakfast, parent and child may go home.
Results
Analysing the study takes time. The results will therefore be discussed later with the treating physician. You will receive a new appointment for this.
A child-friendly sleep study
Read Juna’s story in the sleep lab by clicking on the arrows at the bottom right of the illustrations.