Polysomnography, also called a sleep study, is a comprehensive test used to diagnose sleep disorders. Polysomnography records your brain waves, the oxygen level in your blood, heart rate and breathing, as well as eye and leg movements during the study.
Polysomnography may be done at a sleep disorders unit within a hospital or at a sleep center. While it's typically performed at night, polysomnography is occasionally done during the day to accommodate shift workers who habitually sleep during the day.
In addition to helping diagnose sleep disorders, polysomnography may be used to help initiate or adjust your treatment plan if you've already been diagnosed with a sleep disorder.
When Should One Get It done
Polysomnography monitors your sleep stages and cycles to identify if or when your sleep patterns are disrupted and why.
There are different types of home sleep apnea test devices using different combinations of sensors. They generally record your breathing rate and airflow, as well as oxygen levels and heart rate. One style also incorporates information on blood vessel tone.
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 in about 90 minutes. Sleep disorders can disturb this sleep process.
- Excessive daytime sleepiness
- Early morning headache
- Stopped breathing efforts while sleeping
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