Sleep Study 

After a detailed medical history your doctor will send you to a Sleep Laboratory to have a Diagnostic Sleep Study to determine if you have sleep apnoea and its severity.

Sleep studies are conducted in hospital or private clinics; it requires you to stay overnight. The studies are done by qualified sleep technicians. On the night of the study the patient arrives at the lab between 7 - 8 pm to be connected to equipment that monitors heart, oxygen and brain activity, the technician also records leg movement and snoring. Everything that happens during the night is recorded then this viewed by a sleep physician and he can then make a diagnosis and recommend appropriate treatment.

A sleep study is also known as a polysomnograph - meaning many sleep measures. The most common measures are:

* EEG - electroencephalogram à a measure of electrical signals from the brain, helps determine sleep stages and whether the patient is awake or sleep.

* EOG - electro-oculogram à a measure of eye movement that helps distinguish REM sleep from other sleep.

* EMG - electromyogram à a measure of the activity of the muscles under the chin.

* ECG - electrocardiogram à a measure of the electrical activity of the heart. This measurement is extremely helpful as it can pick up undiagnosed irregularities in heart beat or rhythm.

* Breathing - a small device to detect breathing is generally placed in front of the nose or mouth.

* Breathing effort - a loose elasticised bands are placed around the chest and abdomen to determine breathing effort or whether the body just forgets to breathe.

* Oximeter - used to measure oxygen in blood.

* Leg movement - small devices are stuck on each leg and arms (sometimes), to see whether the patient's legs are moving during the night. This is amportant measurement because it can help diagnose restless legs syndrome.

* Snoring - a microphone in the room measures the level of noise.

* Body position - a device is placed on the chest to determine if the patient is lying on the back, side or front.

While the sleep study is not painful, it tends to be a little uncomfortable. Some people do not sleep at all and need to repeat the study again (the second time the study is usually successful).

Preparation for the study

To help you sleep you may wish to bring your pillow, toiletries, pyjamas and change of clothes for the nest morning. You should also bring your medications. The sleep lab should send out an information package before the study.

See below for some of the recording obtained during the sleep study.

OXYGEN SATURATION

AROUSALS

SLEEP STAGE SUMMARY

APNOEA GRAPH

PLM

BODY POSITION

HEART RATE