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Polysomnogram (PSG)



A sleep study or polysomnogram (PSG) is a test that electronically transmits and records specific physical activities while you sleep. The recordings become data that are analyzed by a qualified sleep specialist to determine whether or not you have a sleep disorder.


Diagnostic overnight PSG: General monitoring of sleep and a variety of body functions during sleep, including breathing patterns along with oxygen levels in the blood, heart rhythms, and limb movements.


During a Polysomnogram:



  • Sticky patches with sensors called electrodes are placed on your scalp, face, chest, limbs, and a finger. While you sleep, these sensors record your brain activity, eye movements, heart rate and rhythm, blood pressure, and the amount of oxygen in your blood.

  • Elastic belts are placed around your chest and belly. They measure chest movements and the strength and duration of inhaled and exhaled breaths.

  • Wires attached to the sensors transmit the data to a computer in the next room. The wires are very thin and flexible. They are bundled together so they don't restrict movement, disrupt your sleep, or cause other discomforts.


PSG results are used to help diagnose:


  • Sleep-related breathing disorders, such as sleep apnea

  • Sleep-related seizure disorders

  • Sleep-related movement disorders, such as periodic limb movement disorder

  • Sleep disorders that cause extreme daytime tiredness, such as narcolepsy (PSG and MSLT results will be reviewed together)


Your doctor also may use a PSG to find the right setting for you on a CPAP (continuous positive airway pressure) machine. CPAP is a treatment for sleep apnea.


Sleep apnea is a common disorder in which you have one or more pauses in breathing or shallow breaths while you sleep. In obstructive sleep apnea, the airway collapses or becomes blocked during sleep. A CPAP machine uses mild air pressure to keep your airway open while you sleep.


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