Polysomnography (PSG) is a comprehensive diagnostic test used to study sleep and diagnose various sleep disorders. Often referred to as a “sleep study,” polysomnography monitors multiple physiological parameters during sleep to provide a detailed picture of a person’s sleep architecture and uncover underlying abnormalities.
What is Polysomnography?
Polysomnography is a multi-channel recording of several body functions while a person sleeps. The word “polysomnography” literally means “many sleep recordings,” reflecting the numerous physiological data points collected simultaneously during the test. It is primarily conducted overnight in a sleep laboratory, though home-based sonnocare versions exist for selected cases.
The main goal of polysomnography is to observe and analyze the different stages of sleep and identify disruptions or disorders. It is the gold standard test for diagnosing conditions such as obstructive sleep apnea (OSA), narcolepsy, restless legs syndrome (RLS), periodic limb movement disorder (PLMD), and other parasomnias (unusual behaviors during sleep).
How Does Polysomnography Work?
During the test, several sensors and electrodes are attached to the patient’s body to monitor different functions, including:
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Electroencephalography (EEG): Records brain wave activity to determine sleep stages.
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Electrooculography (EOG): Measures eye movements, which help distinguish between REM (rapid eye movement) and non-REM sleep.
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Electromyography (EMG): Detects muscle activity, often placed on the chin and legs.
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Electrocardiography (ECG or EKG): Monitors heart rate and rhythm.
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Respiratory sensors: Measure airflow through the nose and mouth, chest and abdominal movement, and oxygen saturation via pulse oximetry.
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Additional sensors: Sometimes include snoring microphones and body position sensors.
These measurements are continuously recorded throughout the night, creating a detailed profile of the patient’s sleep patterns, breathing, limb movements, and cardiac function.
Why is Polysomnography Important?
Sleep is a complex biological process with several stages, including light sleep, deep sleep, and REM sleep. Each stage plays a critical role in physical restoration, memory consolidation, and overall health. Disruptions in normal sleep architecture can lead to daytime fatigue, cognitive impairment, mood disorders, cardiovascular problems, and a decreased quality of life.
Polysomnography helps clinicians identify abnormal events such as apneas (pauses in breathing), hypopneas (shallow breathing), limb movements, or abnormal brain wave patterns. By pinpointing the exact nature and severity of these issues, appropriate treatments—such as continuous positive airway pressure (CPAP) therapy for sleep apnea or medication for restless legs syndrome—can be prescribed.
Who Should Undergo Polysomnography?
Doctors may recommend a polysomnography test if a patient experiences symptoms such as:
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Loud snoring with pauses in breathing
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Excessive daytime sleepiness or fatigue
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Difficulty staying awake during the day
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Unexplained nighttime behaviors (e.g., sleepwalking or talking)
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Chronic insomnia or disrupted sleep
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Suspected narcolepsy or periodic limb movement disorder
The Procedure and What to Expect
Polysomnography is usually performed in a specialized sleep center. The patient arrives in the evening, and technicians attach the sensors and electrodes. After a briefing on the procedure, the patient sleeps overnight while the data is recorded.
The test is painless but requires the patient to sleep in an unfamiliar environment with monitoring equipment attached, which might initially affect sleep quality. The next day, the data is analyzed by sleep specialists who generate a report to aid diagnosis and treatment planning.
Polysomnography is an invaluable tool for understanding the complexities of sleep and diagnosing disorders that profoundly affect health and well-being. By providing objective, detailed information about sleep physiology, it enables targeted treatment that can significantly improve quality of life for individuals suffering from sleep disorders.