How Is Polysomnography Performed?

Reviewed on 1/14/2021


Polysomnography (PSG) is the study of sleep patterns and the body's response to the various stages of the sleep cycle.
Polysomnography (PSG) is the study of sleep patterns and the body’s response to the various stages of the sleep cycle.

The PSG is conducted in a sleep laboratory overnight. The doctor monitors your sleep patterns, sleep continuity, and general biological responses during sleep. Polysomnography examines the brain wave patterns, eye movements, and the tone of the muscles. It also monitors and records the breathing, heart activities, eye movements, brain functions, and ocular function during sleep.

The PSG is performed in the following manner:

  • A variety of sensors are taped to the body parts to record brain waves, eye movements, muscle tone, body movements, heart rhythm, and breathing patterns overnight. No painful equipment (such as needles) is used.
  • The oxygen content of the blood is measured noninvasively with a simple clip on a finger (pulse oximeter).
  • Although there are many connecting wires to the sensors, the patient is free to get up and use the restroom as needed.
  • A trained sleep technologist is present for the entire study duration to oversee the procedure as the set up records the data.
  • During the sleep study, every attempt is made to allow a comfortable night’s sleep. Some people typically sleep better or worse when away from home, but in either case, this does not affect the quality of the sleep study.
  • It could take a couple of weeks before you receive your polysomnography results.
  • Following the sleep study, a physician that specializes in sleep medicine will interpret the recording. The findings will be integrated into your sleep history to make a diagnosis and make the appropriate treatment recommendations.

Purpose of polysomnography

It is used to diagnose and evaluate the types of sleeping disorders. These include the following:

  • Disorders of initiating or maintaining sleep (dyssomnias):
    • Sleep apnea: This is a disorder most prevalent in middle-aged and elderly obese individuals. With this disorder, the muscles of the tongue and the throat relax and close off the airway during sleep. Sleep apnea may cause the patient to snore loudly and gasp for air at night, resulting in daytime sleepiness.
    • Narcolepsy: The patient suffers from excessive daytime sleepiness, sudden attacks of muscle weakness (cataplexy), and hallucinations at sleep onset.
  • Disorders during sleep (parasomnias, including medical, psychiatric, and dental disorders):

Limitations of polysomnography:

The greatest limitations to polysomnography are the differences between the recording conditions and those that are present in the patient's home. The differences between the sleep laboratory and home have the highest effect on the first night of testing.

Detection and elimination of this "first-night effect" can be accomplished by the costly step of recording for multiple nights.

Multiple night recordings are also sometimes necessary to obtain information about problems that appear only sporadically.

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