Polysomnography, often referred to as a sleep study, is a comprehensive diagnostic tool used to evaluate sleep disorders. It records multiple physiological parameters during sleep, providing valuable insights into the quality and architecture of sleep, and helps diagnose conditions such as sleep apnea, narcolepsy, restless leg syndrome, and insomnia.
What is Polysomnography?
Polysomnography is a non-invasive overnight test that monitors a variety of body functions during sleep. The word “poly” means many, and “somno” relates to sleep, reflecting the test’s capability to record multiple sleep-related apnee del sonno variables simultaneously. The data collected allows healthcare providers to analyze sleep stages and detect abnormalities that may affect health and daytime functioning.
How Does Polysomnography Work?
During a polysomnography session, sensors and electrodes are attached to the patient’s scalp, face, chest, limbs, and sometimes other areas to track different bodily functions:
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Electroencephalogram (EEG): Records brain wave activity, helping to identify sleep stages (REM and non-REM sleep).
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Electrooculogram (EOG): Tracks eye movements, which helps distinguish REM sleep.
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Electromyogram (EMG): Measures muscle activity, particularly to detect movements and muscle tone changes.
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Electrocardiogram (ECG): Monitors heart rate and rhythm.
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Respiratory sensors: Detect airflow through the nose and mouth, respiratory effort via chest and abdominal movements, and oxygen levels in the blood using pulse oximetry.
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Leg sensors: Monitor leg movements that might indicate periodic limb movement disorder.
The patient spends the night in a specialized sleep lab where these sensors collect data while the person sleeps naturally. The recording typically lasts for one full sleep cycle, usually 6 to 8 hours.
Why is Polysomnography Important?
Sleep is critical for physical and mental health. Disorders that disrupt sleep can cause daytime fatigue, memory problems, cardiovascular issues, and decreased quality of life. Polysomnography provides a detailed understanding of sleep disruptions, allowing for accurate diagnosis and tailored treatments.
The most common reason for ordering a polysomnography test is to diagnose obstructive sleep apnea (OSA) — a condition where breathing repeatedly stops and starts due to airway obstruction. Sleep apnea is associated with risks like high blood pressure, heart disease, stroke, and diabetes.
Besides OSA, polysomnography helps diagnose:
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Narcolepsy: Excessive daytime sleepiness and sudden sleep attacks.
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Restless Legs Syndrome (RLS): Uncontrollable urge to move the legs.
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Periodic Limb Movement Disorder (PLMD): Involuntary limb jerking during sleep.
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REM Sleep Behavior Disorder: Acting out dreams due to loss of normal muscle paralysis in REM sleep.
Preparing for the Test
Patients are advised to follow specific instructions to ensure accurate results. Avoiding caffeine, alcohol, and certain medications before the test is usually recommended. They should also maintain their regular sleep schedule leading up to the study.
What Happens After Polysomnography?
A sleep specialist reviews the data and writes a detailed report outlining the findings. Based on the diagnosis, treatments may include lifestyle changes, continuous positive airway pressure (CPAP) therapy for sleep apnea, medications, or other interventions.
Polysomnography remains the gold standard for diagnosing complex sleep disorders. By providing a window into the sleeping brain and body, it empowers patients and doctors to improve sleep quality and overall health. If you or a loved one experiences symptoms like excessive daytime sleepiness, loud snoring, or restless legs at night, consulting a healthcare professional about polysomnography might be the first step toward better rest and well-being.