Learn About Polysomnograms

Last updated: April 23, 2019

The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. Read our full medical disclaimer.

Polysomnography is one of the most common tests that doctors use to diagnose a sleep disorder. It is also called a sleep study. During polysomnography, a doctor or a medical technician records a patient’s brain waves and the oxygen level in the patient’s blood. They also take records of the heart rate and the patient’s respiratory rate. The patient’s eye and leg movements also get monitored.

Polysomnography often requires an overnight stay in a sleep disorder unit within a hospital or a sleep center. However, it is also possible to administer the test during the day, in order to accommodate patients who, work graveyard shifts and sleep during the day.

When do I need to undergo Polysomnography?

Polysomnography or PSG can monitor a person’s sleep stages and cycles. This test can help detect when a person’s sleep patterns get disrupted and why.

When a person without any sleep disorder sleeps, the sleep stage begins with a stage called non-rapid eye movement (NREM) sleep. It is at this stage when electroencephalography (EEG) detects a slow down on a person’s brain waves. This stage lasts about an hour or two. The brain activity then picks up again and rapid eye movement (REM) sleep begins. A person experiences dreams during REM sleep. The eyes also move back and forth rapidly, hence the term Rapid Eye Movement. During normal sleep, individual cycles between NREM and REM sleep multiple times. When a person has a sleep disorder, there is a disturbance in this sleep process. Through polysomnography, a doctor can take note of a disturbance in the sleep cycle and what caused it.

A doctor may recommend a polysomnogram if he suspects that a patient has:

What should I do before polysomnography?

Just like with any medical test, there are some things that a person should do prior to polysomnography. A doctor may advise a patient to avoid drinking or eating anything that contains caffeine or alcohol prior to polysomnography. Consuming alcohol and caffeine can result in a change in a person’s sleep patterns. These symptoms may amplify the symptoms of some sleep disorders.

An individual about to have polysomnography should also avoid taking a nap in the afternoon prior to the sleep study. It is also common to require a patient to take a bath or shower beforehand. However, a patient should not put on lotions, colognes, make-ups or gels. These can interfere with the use of the electrodes.

A technician may also have the patient try a positive airway pressure (PAP) machine for sleep apnea. This device delivers a gentle stream of air to a patient during sleep. A Continuous Positive Airway Pressure (CPAP) is a type of PAP machine. This device delivers a constant stream of air that helps keep the air passages open while a patient sleep.

Using a PAP machine during polysomnography can help a technician determine if this is an effective mode of treatment for the patient. The technician can also make adjustments on the CPAP machine to determine the right amount of air flow or air pressure.

What happens during polysomnography?

During polysomnography, a patient sleeps overnight at a sleep center. A technician will place small adhesive sensors called electrodes on the patient’s scalp, chest, temples, and legs. These electrodes will record the needed information and send them to a computer. The gathered information will be available to the doctor for evaluation.

This is a non-invasive procedure. A patient can immediately resume normal day to day activities the morning after a PSG.

The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. Read our full medical disclaimer.

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