Polysomnography is a test or study performed on a person who is fully asleep. Hence, it is also known as sleep study. Polysomnography is basically done to detect sleep disorders. While the patient is asleep, polysomnography records the following:
- breathing cycle
- heart rate
- oxygen level in blood
- brain waves
- muscle tone
- leg movements
- eye movement
The polysomnography test can be done in a sleep center or a special room in the hospital. The patient is usually asked to come late in the evening for the polysomnography test so that the patient can record different sleep patterns while sleeping. The whole process of polysomnography is monitored and then analyzed by an experienced sleep specialist.
A polysomnography test usually records the patient’s body changes between 2 phases i.e. Rapid Eye Movement (REM) and Non-Rapid Eye Movement (NREM). Non-rapid eye movement is further divided into 2 phases:
- light sleep
- deep sleep
When tracking the Rapid Eye Movement (REM) phase, it is generally observed that the patient’s brain activity is very high and the only active parts are the breathing muscles and eyes.
During the phase tracking of non-rapid eye movement (NREM), it is observed that the patient’s brain activity is significantly reduced. Therefore, a person with no sleep disorder will shift between a non-REM to REM phase every 2 hours, with 4 to 6 sleep cycles each night. The sleep specialist carefully monitors the patient’s body responses and sleep cycles, and therefore, detects any disruptions in sleep patterns.