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Polysomnography - Uses and Techniques

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Polysomnography is a diagnostic study of sleeping disorders. Read the article below to learn about the uses and procedures of polysomnography.

Written by

Dr. Saberitha

Medically reviewed by

Dr. Abhishek Juneja

Published At February 6, 2023
Reviewed AtFebruary 6, 2023


Polysomnography is a diagnostic test performed during sleep. The sleep patterns are recorded by medical professionals to diagnose the sleeping disorder. It is also helpful to plan the treatment procedures depending on the sleeping disorders. It is a painless and non-invasive technique. The data is provided in the form of a graph. A video may be recorded by the medical provider to observe the change in posture.

What Are the Various Patterns Measured in Polysomnography?

  • Electroencephalography - The electrical activity of the brain is due to the presence of neurotransmitters. It is used to observe brain activity with the help of brain waves.

  • Electrooculogram - Electrooculogram is used to measure the movement of the eyes. The number of movements and the frequency of movement are assessed.

  • Electromyography - It is used to measure muscle tone during the action. The movement of limbs is analyzed using electromyography. The number and the intensity of the limb movements are measured. Both the upper and lower limbs are observed.

  • Breathing Pattern - The number of inspirations and expiration and the intensity of the respiration are evaluated in the breathing pattern. It also estimates the oxygen saturation level in the blood.

  • Sleep Pattern - The time taken by the individual to fall asleep is assessed. This is known as sleep latency. It is used to observe the amount of sleep that a person gets in the night. The ratio of sleep time to the time in bed is calculated. This is known as sleep efficiency. The pH level (acid-base) of the stomach is examined. It is used to identify the amount of acid secretion during sleep.

How Is the Polysomnography Procedure Performed?

The polysomnography is carried out in the following process;

  • The individuals must remove the ornaments and wear an outpatient dress given in the sleep center.

  • The individual should stay in the sleep center during the night until the completion of the sleep study.

  • The electrodes are attached to the head and body with cables. These metal plates are used to calculate electroencephalography, electrooculogram, and electromyography.

  • A pulse oximeter tool is used to measure the oxygen level in the bloodstream. It is placed over the fingers. It monitors the airflow during sleep.

  • The temperature is adjusted to the normal level in the room. The activity of the individual is monitored before and after sleeping.

  • The lights are turned off. The individual can use a blanket if necessary. It will not interfere with the electrodes attached.

  • If the patient wakes up frequently, then the multiple sleep latency can be calculated.

The same process is repeated daily until the end of the sleep study.

What Are the Instructions to Follow During Polysomnography?

There are a few general instructions to follow during polysomnography. They are as follows;

  • The individual should answer certain questions related to bedtime and sleep provided by the medical professional. Avoid taking short naps in the afternoon during the sleep study.

  • The vitamin supplements and the medications taken for systemic disease must be informed to the medical professional. Avoid sedatives during the study because these drugs may influence sleep.

  • The individual must avoid caffeine-related drinks during the sleep study. Try to stop it a few days before the sleep study or polysomnography.

  • Take showers before going to the sleep centers. It helps in sleeping. Do not use body lotions as it affects the electrodes.

  • The person undergoing this test should report in the evening to finish a few protocols.

  • They are then allowed to enter a sleeping room that is dark, cold, and quiet to induce sleep.

  • At least two hours of sleep is necessary to caliber the recordings.

What Are the Uses of Polysomnography?

Polysomnography is used to evaluate sleeping dysfunctions. They are as follows;

  • Sleep Apnea - Sleep apnea is a condition in which the breathing cycle stops continuously and restarts during sleep. So the individual tries to gasp for air after the pause. This disturbs sleep, and the individual wakes up frequently during the night. A loud sound is heard from the patient during snoring. This results in restlessness and fatigue during the daytime.

  • Narcolepsy - Narcolepsy occurs due to nervous disorders. The patient falls asleep during the day and stays awake at night. There is increased drowsiness during the day. It affects teens. There is a fragmented sleep pattern in narcolepsy.

  • Seizure Disorders - The abnormal electrical activity of the brain results in multiple seizures. The patient undergoes stress and is unable to sleep. Multiple seizures in a day make the patient unconscious in the worst cases. It occurs due to metabolic disturbances in the body.

  • Restless Legs Syndrome - The individual has an intense feeling of moving the leg, especially during sleep. This frequent sensation interferes with the sleep cycle. Eventually, it leads to sleep deprivation. It mostly affects females. The limb movement lasts for 40 seconds to one minute. This urge causes a pulling sensation and disturbs sleep.

  • Rapid Eye Movement (REM) Sleep Behavior Disorder - Vivid dreams during sleep cause rapid eye movement (REM) sleep behavior disorder. It occurs due to the degeneration of neurons in the brain. Some individuals do explicit actions like talking, jumping, and punching during sleep. It is diagnosed using polysomnography and can be treated with medications.

  • Insomnia - Chronic condition of trouble falling asleep is called insomnia. The person is unable to sleep and does not feel fresh after waking up. It impacts mental health. The individual has inconsistent sleep patterns. The person feels irritated and has constant mood swings. So sleep study is used to diagnose insomnia.


Polysomnography can also be performed at home, but it has limited sensors. However, a sleep study does not require complete sleep. A home sleep study is mainly used for diagnosing obstructive sleep apnea. If the sleep study is done at sleep centers, then the sensors are removed in the morning. The individual can continue the normal activities in the morning. The results of the sleep study made in sleep centers are given in three weeks. Untreated sleeping disorders can lead to an increase in blood pressure, depression, stroke, and cardiac issues. However, these tests help determine the issue so that appropriate treatment can be started to improve the patient's quality of life.

Frequently Asked Questions


Are Polysomnography and EEG Considered the Same?

No, polysomnography and EEG (electroencephalography) are not the same. EEG is one of the components of polysomnography. Polysomnography (PSG) is a comprehensive sleep study that combines multiple physiological measurements like EOG (eye movements), heart rate (ECG), muscle activity (EMG), EEG, respiratory function, and more to assess and evaluate sleep patterns and disorders whereas EEG is a technique used to record and monitor the electrical activity of the brain.


What Is the Required Duration of Sleep for a Sleep Study?

The duration of sleep necessary to conduct polysomnography, commonly referred to as a sleep study, may be subject to variation based on the precise research objectives as well as the operating procedures implemented by the healthcare provider or sleep center. Generally, a standard overnight sleep study involves monitoring sleep patterns and assessing for sleep disorders during a single night of sleep. The typical duration for an overnight sleep study is around 7-8 hours.


Is Polysomnography Considered a Medical Procedure?

Yes, polysomnography is a procedure performed in a sleep laboratory or sleep center to assess and evaluate sleep patterns and diagnose sleep disorders. It involves the simultaneous monitoring and recording of various physiological parameters during sleep. During polysomnography, electrodes and sensors are placed on the individual's body to measure and record specific signals. The individual is typically required to spend a night at the sleep center, where trained technicians monitor and record the data throughout the sleep period. Sleep specialists then analyze the collected data to identify different stages of sleep, detect any abnormalities or sleep disorders, and formulate appropriate treatment plans.


What Level of Accuracy Can Be Expected From Polysomnography?

Polysomnography is considered one of the most accurate diagnostic tools for assessing sleep patterns and diagnosing sleep disorders. It provides comprehensive data on various physiological parameters during sleep, allowing sleep specialists to make accurate assessments and diagnoses. The precision of polysomnography relies on various aspects, such as the proficiency of the sleep technicians who administer the examination, the caliber of equipment utilized, and the skills of sleep specialists in interpreting the results. Highly reliable and accurate results can be obtained through polysomnography when it is conducted by skilled experts utilizing top-notch equipment and adhering to standardized protocols.


For What Purposes Is the Polysomnography Test Utilized?

Polysomnography is a valuable diagnostic tool used in sleep medicine to assess and evaluate sleep patterns and diagnose various sleep disorders. Some of the common uses are

- Sleep apnea diagnosis.

- Narcolepsy diagnosis.

- Evaluation of sleep-related-movement disorders.

- Evaluation of parasomnias.

- Assessment of sleep quality.

- Evaluation of insomnia.

- Titration of continuous positive airway pressure.


What Is the Purpose of Conducting Polysomnography?

Polysomnography is done to diagnose and evaluate various sleep disorders. It helps healthcare professionals assess and monitor the physiological changes that occur during sleep. PSG is commonly used to diagnose conditions such as sleep apnea, insomnia, narcolepsy, periodic limb movement disorder, and other sleep-related breathing disorders.


What Are the Five Primary Sleep Disorders?

There are several sleep disorders recognized by medical professionals, but here are five major sleep disorders:

- Insomnia: The inability to fall asleep or stay in that state for the desired duration, or even not having a restful sleep despite sufficient opportunities, is called insomnia.

- Sleep Apnea: While one is asleep, breathing is repeatedly disrupted in sleep apnea.

- Narcolepsy: The nervous system condition known as narcolepsy causes the brain to struggle with controlling normal sleep and wake patterns.

- Restless Legs Syndrome: The restless legs syndrome triggers an urge to shift legs and results in unpleasant sensations such as crawling, tingling, or burning.

- Parasomnias: Parasomnias refer to a cluster of sleep disorders that involve unusual actions, movements, or perceptions while sleeping.


Can Polysomnography Be Conducted in a Home?

Yes, polysomnography can be conducted at home in certain cases. Traditionally, polysomnography is performed in a sleep laboratory or a specialized sleep center where patients spend the night while their sleep patterns and physiological parameters are monitored. However, modern and advanced technologies have led to the development of home sleep testing devices that allow for polysomnography to be performed in the comfort of a patient's own home. Home sleep testing devices are portable and user-friendly, typically consisting of sensors that monitor parameters such as airflow, breathing effort, oxygen saturation, heart rate, and body position.


How Long Does It Take to Receive Polysomnography Results?

Several factors can affect the duration of time it takes to receive the results of polysomnography, such as the laboratory or sleep center where the test was performed and the workload of the interpreting sleep specialist. Generally, it takes about 1 to 2 weeks to receive the results of a PSG test.


What Steps Should Be Taken to Prepare for Polysomnography?

Preparing for polysomnography involves a few essential steps to ensure accurate and effective monitoring during the sleep study. Here are some general guidelines to follow:

- Consult with the healthcare provider.

- Avoid caffeine and stimulants.

- Maintain the usual routine.

- Shower and avoid using oils and lotions.

- Avoid napping.

- Follow instructions regarding medications.

- Wear comfortable clothing.

- Inform the sleep center of special needs.

- Limit alcohol consumption.

- Arrive on time


Who Is Qualified to Perform Polysomnography?

The individuals involved in conducting polysomnography typically involve sleep technologists, respiratory therapists, and sleep physicians. It is important to note that different healthcare facilities, countries, and professionals have different roles and responsibilities. Besides doctors and nurses, there may be other helpers like office staff who help organize and plan the sleep study.


What Are the Drawbacks of Polysomnography?

While polysomnography is considered the standard for diagnosing sleep disorders, it does have certain disadvantages like:

- High cost.

- Inconvenience and discomfort of spending a night away from the comfort of the home.

- Limited accessibility of sleep centers in rural or remote areas.

- Lack of a natural sleep environment.

- Invasive nature involves the attachment of multiple sensors and electrodes to the body.

- Specific focus on overnight sleep.

- Observer effect involves the presence of monitoring equipment and healthcare professionals, which may influence the individual’s sleeping pattern or behavior.


Is ECG Part of Polysomnography?

Yes, polysomnography typically includes the monitoring of electrocardiogram (ECG) in addition to other physiological parameters. ECG measures the electrical activity of the heart and is an important component of polysomnography to assess cardiac function during sleep.


Is Polysomnography Considered Hard?

Polysomnography is a specialized medical test that requires specific training and expertise to perform accurately. While it may be challenging for individuals who are not trained in sleep medicine, it is not inherently difficult for trained professionals.


What Are Three Common Indications of a Sleeping Disorder?

Three common signs that may indicate the presence of a sleeping disorder:

- Excessive daytime sleepiness.

- Snoring or breathing problems during sleep.

- Difficulty falling asleep or staying asleep.

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Dr. Abhishek Juneja
Dr. Abhishek Juneja



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