20 Jul 2018


Polysomnography is a test conducted to study sleep and to diagnose a variety of sleep disorders. Some people refer to polysomnography (PSG) as a sleep study. Sleep technologists perform the tests which are typically conducted in hospitals, or dedicated sleep centres.

Purpose of polysomnography:

Polysomnography is used not only to help diagnose a variety of sleep disorders but also to learn whether adjustments to treatment plans are needed or if the current treatment plan is effective. The sleep study itself  provides specific information to sleep technologists (through equipment and observation), including:

  • Blood Oxygen Levels
  • Breathing Rates and Patterns
  • Body Positioning
  • Brain Waves (EEG)
  • Eye Movements
  • Heart Rates and Rhythms
  • Leg Movements
  • Sleep Stages
  • Snoring and Noises Made While Sleeping
  • Unusual Movements or Behaviors

Of course, all of this is done while patients are sleeping.

Polysomnography is performed in one of these cases:

Physicians order polysomnography for many different reasons, including concerns that the patients may be experiencing one of the following:

  • Sleep Apnea
  • Periodic Limb Movement Disorder
  • Narcolepsy
  • REM Sleep Behavior Disorder
  • Unusual Behaviors During Sleep
  • Unexplained Chronic Insomnia

Preparing Your Patient for a Polysomnography:

  1. One important thing you need to do is inform patients not to take alcohol and caffeine during the afternoon and evening preceding the polysomnography. Prepare your patient for the fact that this is an overnight test, and encourage your patient to bring items essential to their bedtime routines as well as his or her pajamas – so your patient can sleep comfortably.
  2. Patients may have a little difficulty falling asleep due to being in unfamiliar surroundings, a little bit of nervousness, and the electrodes and wires may make getting comfortable a little more challenging than normal. Encourage them to bring a book to read or something soothing to help them relax before sleep.
  3. Let the patient know your role in the sleep study by explaining that you will monitor their brain waves, eye movements, heart rates, breathing patterns, sleeping positions, limb movements, blood oxygen levels, and snoring and other noises they may make while sleeping.
  4. Explain to your patient that you will study those things by watching the recordings while he or she sleeps that are generated by tiny sensors on his or her scalp, chest, and legs, as well as a sensor that attaches to the tip of the patient’s finger to monitor blood oxygen levels.


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