What is Polysomnography?
Polysomnography (PSG), also called a sleep study, is a comprehensive test used to diagnose sleep disorders. PSG records your brain waves, the oxygen level in your blood, heart rate and breathing, as well as eye and leg movements during the study.
PSG can be done at a sleep disorders unit within a hospital or at a sleep center. While it's typically performed at night,
PSG is occasionally done during the day to accommodate shift workers who habitually sleep during the day.
In addition to helping diagnose sleep disorders, PSG may be used to help initiate or adjust your treatment plan if you've already been diagnosed with a sleep disorder.
Why is Polysomnography test important?
PSG monitors your sleep stages and cycles to identify if or when your sleep patterns are disrupted and why. The normal process of falling asleep begins with a sleep stage called non-rapid eye movement (NREM) sleep. During this stage, your brain waves, as recorded by electroencephalography (EEG), slow down considerably.
Your eyes don't move back and forth rapidly during NREM, in contrast to later stages of sleep. After an hour or two of NREM sleep, your brain activity picks up again, and rapid eye movement (REM) sleep begins. Most dreaming occurs during REM sleep.
You normally go through multiple sleep cycles a night, cycling between NREM and REM sleep for about 90 minutes. Sleep disorders can disturb this sleep process.