Polysomnography (Sleep Study)

What is polysomnography (PSG)?

Polysomnography, also known as PSG or sleep study, is a test used to diagnose sleep disorders. It is done while you are fully asleep. After you complete the overnight study, a specialist will interpret your sleep pattern data.

As part of your PSG, your doctor will examine the following to chart your sleep cycles and identify any disruptions in your sleep patterns:

  • Heart rate
  • Brain waves
  • Body position
  • Eye movements
  • Limb movements
  • Breathing patterns
  • Blood oxygen level
  • Chest and abdominal movements
  • Snoring and other noises you may make during sleep

Why do you need polysomnography (PSG)?

Your doctor may recommend a polysomnogram test if they suspect that you have any of the following.

  • Central sleep apnoea, a disorder in which breathing constantly stops and restarts during sleep. This happens because your brain fails to send correct signals to the muscles that help you with breathing.
  • Obstructive sleep apnoea (OSA), a disorder in which your throat muscles periodically relax during sleep and inadvertently block your airway.
  • Periodic limb movement disorder, in which you involuntarily flex and extend your legs while sleeping. This condition may be associated with restless legs syndrome.
  • Narcolepsy, a brain condition that makes you suddenly fall asleep at inappropriate times.
  • Rapid eye movement (REM) sleep behaviour disorder, which makes you act out dreams as you sleep.
  • Chronic insomnia, which means that you have trouble falling asleep or staying asleep.
  • Unusual behaviours during sleep

If sleep disorders go untreated, they can raise your risk of:

What are the risks and complications of polysomnography (PSG)?

Polysomnography is a non-invasive and painless test. In general, the risks are low.

You may however experience skin irritation caused by the adhesive used to attach the electrodes to your skin.

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