How does polysomnography work?

Polysomnography is the best-known method for examining sleep disorders and takes place in special sleep laboratories. Here we explain what happens during polysomnography and how it helps to identify sleep problems.

Table of Contents

1. What is polysomnography?
2. How does polysomnography work?
3. How does polysomnography work?
4. Who needs polysomnography?
5. Conclusion

1. What is polysomnography?

Polysomnography (PSG for short) is a procedure for studying sleep in which various biological parameters are measured during sleep and then evaluated. This allows sleep behavior to be comprehensively examined on a physiological level and provide information about how long it takes to fall asleep, interruptions in sleep and other abnormalities. In this way, sleep problems, especially with organic causes, can be identified - for example movement disorders or pauses in breathing (Sleep apnea).

2. How does polysomnography work?

The entire body function changes during sleep, which is why polysomnography collects a lot of different information that can ultimately be put together and get the clearest picture possible. Among other things, brain waves, eye movements, cardiac and respiratory function as well as muscle activity are measured and recorded during sleep using well-known medical procedures (ECG, EEG, ...).

This allows the body to be examined in its entirety during sleep, whereupon sleep problems and potential causes become clear. For example, you can find out whether the patient has a healthy sleep structure and goes through all sleep phases or moves unusually at night.

These parameters are recorded during polysomnography:

• Brain waves using EEG (electroencephalography)
• Eye movement using EOG (electrooculography)
• Tension tone of muscles using EMG (Electromyography)
• Heart rate and heart rhythm using ECG (electrocardiogram)
• Body temperature
• Breathing flow and breathing movement
• Oxygen content in the blood
• Leg movement
• Body position

3. How does polysomnography work?

The examination is quite comprehensive and usually takes place under observation in a sleep laboratory. But there is also the option of carrying out an outpatient screening at home beforehand, a so-called polygraphy. The patient receives a small device to take home that monitors, among other things, the pulse rate, oxygen saturation of the blood and respiratory function overnight. A polygraph is often the first step in getting to the bottom of sleep problems. If there are any abnormalities, this is often followed by an inpatient polysomnography in the sleep laboratory. There you will be looked after overnight by trained staff.

The patient spends the night in the sleep laboratory in a monitored single room. There he prepares for sleep as usual and is then connected to all monitoring devices. To do this, many small electrodes (sensors) are glued directly to the skin on the head and the rest of the body. They are networked via cables with a portable measuring device so that the patient remains mobile at night and can, for example, go to the toilet without disconnecting the electronic connections. Once all preparations have been made, the staff leaves the room, goes to the monitoring room and the patient can lie down in bed and sleep.

The next morning all electrodes are removed again and the results of the examination are evaluated. These are then often discussed in a separate appointment.

4. Who needs polysomnography?

Polysomnography is usually an option if there are serious sleep disorders and outpatient diagnostic procedures do not provide sufficient information.

Polysomnography is often used for…

• Sleep apnea (stopped breathing at night) and other breathing problems
• Insomnia (Persistent difficulty falling asleep and staying asleep)
• Narcolepsy (sleep attacks & drowsiness)
• Restless Legs Syndrome (RLS) and other movement disorders
• Unusual behavior, e.g. b REM sleep disorder, Sleepwalking

The family doctor or ENT doctor usually decides whether the examination in the sleep laboratory is necessary.

5. Conclusion

• Polysomnography is a procedure for examining sleep in order to identify sleep disorders and their causes.

• In polysomnography, brain activity, cardiac and respiratory function, eye movement and many other physiological parameters are analyzed using electrodes and measuring devices.

• Polysomnography takes place in a sleep laboratory and is suitable for people who suffer from sleep disorders such as sleep apnea, insomnia or RLS.