Polysomnography is the test or the study performed on a person, who is completely asleep. Hence, It is also known as the sleep study. Polysomnography is basically done to detect sleeping disorders. Polysomnography records the following while a patient is asleep:
- Breathing cycle (respiration)
- Heart rate
- Level of oxygen in the blood
- Brain waves
- Muscle tone
- Leg Movements
- Eye movements
A polysomnography test may be performed at a sleep center or in a special room in the hospital. The patient is usually asked to come in the late evening for the polysomnography test, in order to record the various sleep patterns while the patient is asleep. The entire process of polysomnography is being monitored and then analyzed by an experienced sleep specialist. Polysomnography test usually records the patient’s body shifts between 2 phases i.e. Rapid eye movement (REM) and Non-rapid eye movement (NREM). Non-rapid eye movement is further divided into 2 stages:
- Light sleep
- Deep sleep
While tracking the phase of rapid eye movement (REM), it is usually observed that the activity of the patient’s brain is very high and the only active parts are the breathing muscles and eyes.
While tracking the phase of non-rapid eye movement (NREM), it is observed that the activity of the patient’s brain is quite low. Hence, a person without any sleep disorders will shift between Non-REM to REM phase in every 2 hours, having 4 to 6 sleep cycles each night. The sleep specialist carefully monitors the body reactions and the sleep cycles of the patient, and hence, detect any disruptions in the sleep pattern.