All about sleep studies
Depending on the country you live in, sleep studies may be performed at home or in a sleep lab. Studies performed in the sleep lab are normally called a polysomnography study, or PSG whereas studies performed in the home may be conducted through a polygraphy study, or PG, or even by using a sleep screening device. Regardless which of these studies is applicable in your country, they are used to demonstrate whether or not you have sleep apnoea and, if so, how severe it is. The main "score" you get from a sleep study is called an apnoea-hypopnea index, or AHI. Your AHI score indicates the number of apnoeas and hypopneas you experience per hour during the sleep study1.
|Severity of sleep apnea||AHI (per hour)|
|Normal||Less than 5|
|Mild||5 to 15|
|Moderate||15 to 30|
In addition to your AHI, the sleep study will also record the oxygen levels in your blood, which might be contributing to excessive daytime sleepiness.
Home or sleep lab?
Your clinician will recommend the appropriate sleep study for you. Depending on the country you live in and your specific needs, the sleep study may be conducted in the sleep lab or in your home. Read on to learn the differences between each.
In a sleep lab or hospital, clinical staff will place sensors on your body to monitor your sleep.
Sensors are placed:
- On your chest to monitor heart activity
- Close to your eyelids to measure which stage of sleep you're in (that is, REM or non-REM sleep)
- On your head to measure electrical signals from the brain
- On your legs to assess muscle activity
You will also be fitted with:
- A nasal cannula to monitor breathing
- An oximeter on your finger to record oxygen levels
- Bands around your chest and stomach to measure breathing effort
With your permission, staff may also need to film the sleep study to gain more insight into your sleeping behavior.
During this type of study, you will be required to stay overnight at the facility, so it's a good idea to get comfortable and take everything you need for your usual sleeping routine, including pajamas and toiletries.
Home sleep testing
A home sleep study is normally conducted with a polygraphy device or a specific sleep screening device, and provides the added comfort and convenience of being in your own home. Before a polygraphy home sleep study night, a sleep technician will help you to apply the required sensors and show you how to use the recording device during the night. If you are asked to use a sleep screening device, then the sleep technician will show you how to attach it and use it during the night.
On the night that you have been scheduled to conduct the home test, you'll follow your normal evening routine, prepare for sleep, attach everything as you've been shown, and start the recording. In the morning, you remove everything as previously demonstrated and return the recording device to the sleep lab or hospital.
A typical home study device will include a one or two chest belts, a nasal cannula, an oximeter and a recording device.
A sleep screening study can be performed using ResMed’s ApneaLinkTM Air, a compact, lightweight and easy-to-use home sleep testing device.
After your sleep study
Once your doctor receives the results of your sleep study, he/she will discuss them with you. You can then discuss your condition, its severity and its possible effects on your health, as well as explore your treatment options.