Polysomnography (PSG) is a sophisticated diagnostic tool used to study sleep patterns and identify various sleep disorders. Often referred to as a “sleep study,” polysomnography records multiple physiological signals during sleep to provide a detailed picture of how an individual sleeps. This test plays a crucial role in diagnosing conditions such as sleep apnea, narcolepsy, restless leg syndrome, insomnia, and other sleep-related problems.

What is Polysomnography?

The term “polysomnography” comes from the Greek words “poly,” meaning many, “somno,” meaning sleep, and “graphy,” meaning recording. Essentially, it is a multi-parameter test that monitors several body functions during sleep, including cpap brain activity, eye movements, muscle activity, heart rate, respiratory effort, airflow, and blood oxygen levels.

A typical polysomnography study is conducted overnight in a specialized sleep laboratory or sometimes at home with portable devices. The patient arrives in the evening, and a trained technician attaches small sensors to the scalp, face, chest, limbs, and sometimes other parts of the body using adhesive patches and wires. These sensors collect data while the patient sleeps, usually for 6 to 8 hours.

Parameters Measured in Polysomnography

• Electroencephalogram (EEG): Records brain wave activity to determine sleep stages, including light sleep, deep sleep, and REM (rapid eye movement) sleep.

• Electrooculogram (EOG): Tracks eye movements, crucial for identifying REM sleep phases.

• Electromyogram (EMG): Measures muscle activity, especially in the chin and legs, to detect movements or muscle tone changes during sleep.

• Electrocardiogram (ECG or EKG): Monitors heart rate and rhythm.

• Respiratory Effort: Sensors measure the effort made by chest and abdominal muscles to breathe.

• Airflow: Measures air movement through the nose and mouth to detect breathing interruptions.

• Pulse Oximetry: Records blood oxygen levels to detect drops caused by breathing pauses.

Why is Polysomnography Important?

Sleep disorders can significantly affect quality of life and overall health. Conditions like obstructive sleep apnea (OSA) can lead to daytime fatigue, impaired concentration, hypertension, heart disease, and even stroke if left untreated. Polysomnography allows doctors to pinpoint these disorders accurately, facilitating timely and effective treatment.

For example, in OSA, polysomnography detects repeated pauses in breathing (apneas) or shallow breathing (hypopneas) during sleep, alongside drops in blood oxygen levels and sleep fragmentation. This detailed information helps in tailoring treatments such as CPAP (Continuous Positive Airway Pressure) therapy, lifestyle changes, or surgery.

Types of Polysomnography

• In-lab Polysomnography: Conducted in a sleep center under supervision. It provides the most comprehensive data.

• Home Sleep Apnea Testing (HSAT): A simplified version focusing mainly on respiratory parameters, suitable for suspected sleep apnea but less comprehensive.

What to Expect During the Test?

Polysomnography is non-invasive and painless, though some patients may find the sensors uncomfortable initially. During the test, the patient sleeps while data is continuously recorded. Technicians monitor the study remotely to ensure quality data collection.

After the study, a sleep specialist reviews the results to analyze sleep stages, breathing patterns, oxygen levels, and movements. The findings form the basis for diagnosis and treatment planning.

Polysomnography is a vital tool in the field of sleep medicine, offering invaluable insights into the complexities of human sleep. By enabling the diagnosis of a wide range of sleep disorders, it helps improve patients’ health, safety, and quality of life. If you experience persistent daytime sleepiness, loud snoring, or other symptoms of sleep disorders, consulting a healthcare professional about polysomnography could be the first step toward restful and restorative sleep.