Polysomnography (PSG) is a comprehensive, multi-parameter diagnostic test used primarily to evaluate sleep disorders. It involves recording various physiological signals during sleep, providing detailed insights into sleep architecture, breathing patterns, muscle activity, and brain function. As sleep problems affect millions worldwide, polysomnography has become a gold standard in diagnosing conditions such as sleep apnea, narcolepsy, restless leg syndrome, and other sleep-related disorders.
What is Polysomnography?
The term “polysomnography” comes from Greek roots meaning “many sleep recordings.” During a PSG test, a patient undergoes overnight monitoring in a sleep laboratory or sometimes at home using portable equipment. Sensors and electrodes are apnee del sonno attached to the patient’s scalp, face, chest, limbs, and sometimes the abdomen to continuously record brain waves (EEG), eye movements (EOG), muscle activity (EMG), heart rate (ECG), airflow, respiratory effort, oxygen saturation, and limb movements throughout the sleep cycle.
How Does Polysomnography Work?
When a person sleeps, their brain cycles through different stages, including light sleep, deep sleep, and REM (rapid eye movement) sleep. Polysomnography records these stages by monitoring brain waves and eye movement. Simultaneously, it tracks breathing and cardiovascular parameters to detect any abnormalities such as pauses in breathing or irregular heart rhythms.
The data collected are analyzed by a sleep specialist to identify disruptions or abnormal patterns. For example, in obstructive sleep apnea (OSA), the test reveals repeated episodes of airflow reduction or cessation despite ongoing respiratory effort. This helps not only confirm the diagnosis but also gauge the severity of the condition.
What Conditions Does Polysomnography Diagnose?
Polysomnography is primarily used to diagnose:
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Obstructive Sleep Apnea (OSA): Characterized by repeated upper airway obstructions during sleep, causing intermittent hypoxia and fragmented sleep.
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Central Sleep Apnea: Where the brain fails to send proper signals to breathe.
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Narcolepsy: A neurological disorder causing excessive daytime sleepiness and sudden muscle weakness.
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Restless Leg Syndrome (RLS) and Periodic Limb Movement Disorder: Conditions involving involuntary limb movements that disrupt sleep.
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REM Sleep Behavior Disorder: Where patients physically act out vivid dreams during REM sleep.
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Insomnia and Other Sleep Disorders: Polysomnography helps identify underlying causes.
Why is Polysomnography Important?
Sleep is critical for physical and mental health. Disrupted or poor-quality sleep can lead to daytime fatigue, cognitive impairment, mood disorders, and increased risk of cardiovascular disease. By accurately diagnosing sleep disorders, polysomnography enables targeted treatment—whether continuous positive airway pressure (CPAP) therapy for sleep apnea, medications for narcolepsy, or lifestyle adjustments for other conditions.
Without polysomnography, many sleep disorders would remain undetected or misdiagnosed, leading to ineffective treatment and worsening health outcomes.
The Procedure and Patient Experience
A typical polysomnography test requires the patient to spend a night at a sleep center. Sensors are applied to the skin with adhesive patches or electrodes. Though the equipment may feel cumbersome at first, patients generally adapt quickly. The environment is controlled to simulate normal sleeping conditions, and technologists monitor the study remotely.
In recent years, home sleep testing devices have gained popularity for simpler cases like suspected moderate obstructive sleep apnea. While less comprehensive than laboratory PSG, these portable tests offer convenience and cost savings.
Polysomnography remains the cornerstone of modern sleep medicine, providing vital insights that guide effective diagnosis and treatment of sleep disorders. As awareness of sleep health grows, this diagnostic tool is increasingly recognized for its role in improving overall well-being and quality of life. For anyone experiencing chronic sleep problems, consulting a sleep specialist about polysomnography may be the first step toward restful nights and healthier days.