Sleep Study : Learn About The Procedure

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Sleep is an important component of a healthy lifestyle. Disorders of sleep can lead to stress and reduction in productivity. Sleep study, also known as polysomnography, is one of the methods used for diagnosing sleep related disorders.

Falling asleep happens in stages; the first stage of sleep is NREM (non rapid eye movement) wherein the brain wave slow down and the eyes remain relatively still. NREM is followed by REM (rapid eye movement) stage during which the brain activity increases and the closed eye moves rapidly, this is also the stage where we dream. Many disorders of sleep affect this stage. Complete sleep is a period cycling of NREM and REM at intervals of about ninety minute; about four to six times.

Sleep study is a method by which your doctor gathers information about various variables while you sleep like your heart rate, your breathing rate, whether you snore or not, your brain waves, movement of different limbs during sleep, oxygen level in your blood and temperature. Correlating these variables will help your doctor arrive to a conclusion on the cause of the disorder.

Procedure of Sleep Study 

Sleep study is conducted in a special sleep lab which may be present in a hospital or at an independent sleep testing facility. You will be requested to reach the sleep lab by evening; you will be spending the night in the sleep lab. The sleep lab is like a hotel room but with various instruments and cameras to record your sleep effectively. You will be attached to various monitors for the test, they are:

  • Leads for electrocardiogram to record the activity of your heart
  • Pulse oximeter: a small probe is attached to your finger or ear to measure the level of oxygen in your blood
  • Electrodes will be placed on your scalp to measure brain waves
  • A microphone will be attached to your clothe or placed nearby to record snoring
  • Electrodes will be placed on different muscles to record movement during sleep
  • Breathing rate monitor
  • Device to monitor the movement of your eyes

Throughout the procedure there will be technician monitoring these parameters, you will be able to communicate with them if you need assistance.

There are different types of sleep studies like:

  • Diagnostic polysomnography
  • Split-night polysomnography: if there is high degree on airway obstruction, during sleep, during the first two hours, you will be put on a positive airway pressure machine, which controls the airflow through your airway and ensures that your airway stays open all the time. This helps in titrating the pressure required to keep the airways open and hence helps in deciding the course of treatment
  • Home study: using a standard monitor it is possible to conduct a sleep study at home. Although this measures less number of variables as a complete sleep study done in a sleep lab, it helps your doctor decide the treatment plan.

Multiple sleep latency test and maintenance of wakefulness tests are done with or after a sleep study to further aid in diagnosis.

Indications for Sleep Study

Sleep study will be requested by your doctor if your doctor suspects:

Preparation for Sleep Study

To prepare for the sleep study, you will be requested to not nap on the day of the test. Your doctor will record the list and schedule of medications that you have been taking for aiding you in your sleep. It is advisable to follow your normal routine before the test. If possible abstain from strenuous exercise three hours before your sleeping time. Take a set of comfortable clothes with you to the sleep lab, as you will be residing there overnight.

Complications of Sleep Study 

Sleep study is a non invasive tests with nearly no complications. Some individuals may be allergic to the glue used in adhesives to fix the sensors and may develop redness, which resolves on its own.

Results of Sleep Study

The results of the sleep study are prepared by and studied by your doctor to reach a tentative diagnosis. Your doctor will discuss them with you and help you decide the further course of the treatment.


  • Polysomnography: a systematic review, Technol Health Care,  1997; 5(4):285-305 (ISSN: 0928-7329), Bloch KE
  • Iber, C; Ancoli-Israel, S; Chesson, A; Quan, SF. The AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology and Technical Specifications. American Academy of Sleep Medicine. Westchester: 2007.