Polysomnography (PSG) is a comprehensive, multi-parameter diagnostic test that records and analyzes physiological functions during sleep. It is widely regarded as the gold standard in evaluating sleep disorders, providing invaluable data that help clinicians understand the complexities of sleep and identify disruptions affecting health and quality of life.
What is Polysomnography?
The term “polysomnography” combines “poly” (many), “somno” (sleep), and “graphy” (recording). This diagnostic procedure involves simultaneous monitoring of various body functions while a patient sleeps, capturing detailed information polisonnografia on brain activity, eye movements, muscle activity, heart rhythm, respiratory effort, airflow, and blood oxygen levels.
A typical polysomnography test is conducted overnight in a sleep laboratory or specialized clinic, where the patient is hooked up to sensors that do not interfere with natural sleep but continuously record physiological signals. Data from these sensors are transmitted to a computer system, which sleep technologists and physicians analyze to identify abnormalities.
Key Parameters Measured in Polysomnography
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Electroencephalography (EEG): Measures brain waves to determine sleep stages, including REM (rapid eye movement) and non-REM sleep.
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Electrooculography (EOG): Records eye movements to help differentiate between sleep stages, especially REM sleep.
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Electromyography (EMG): Measures muscle activity, typically from the chin and legs, detecting movements and muscle tone changes.
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Electrocardiography (ECG): Monitors heart rate and rhythm during sleep.
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Respiratory Channels: Track airflow through the nose and mouth, respiratory effort via chest and abdominal movements, and oxygen saturation using pulse oximetry.
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Other Sensors: Snoring sounds, body position, and limb movements can also be monitored.
Clinical Uses of Polysomnography
Polysomnography is primarily used to diagnose a variety of sleep disorders, including:
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Obstructive Sleep Apnea (OSA): Characterized by repeated episodes of partial or complete airway obstruction, causing breathing interruptions and fragmented sleep.
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Central Sleep Apnea: Involves disruptions in brain signaling to respiratory muscles.
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Narcolepsy: Identified by abnormal REM sleep patterns and excessive daytime sleepiness.
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Periodic Limb Movement Disorder: Characterized by repetitive limb movements causing sleep disruption.
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REM Sleep Behavior Disorder: Where patients act out their dreams due to a lack of normal muscle paralysis during REM sleep.
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Insomnia and Hypersomnia: PSG may be used when the cause of these disorders is unclear.
The Procedure and Patient Experience
Before the test, patients are advised to maintain a regular sleep schedule and avoid caffeine or alcohol. At the sleep center, trained technologists attach electrodes and sensors using adhesives and straps, which are connected to the monitoring device. Although sleeping with sensors can feel unusual at first, patients typically adapt quickly.
Throughout the night, technologists monitor the signals remotely to ensure data quality and to note any unusual events. After the test, the collected data undergo detailed analysis by sleep specialists who interpret the results and prepare a report with diagnosis and treatment recommendations.
Importance and Advances
Polysomnography remains crucial for diagnosing sleep disorders that, if left untreated, can lead to serious health issues like cardiovascular disease, diabetes, and impaired cognitive function. Advances in technology have improved data accuracy and patient comfort, and portable home PSG devices are becoming more common for simpler cases.
In conclusion, polysomnography is an essential tool in sleep medicine. By providing a window into the body’s nighttime processes, it enables early diagnosis and tailored treatment, significantly improving patients’ sleep quality and overall health.
