Sleep laboratory

Asleep study, orovernight polysomnogramis a very thorough look at your sleep patterns. We monitor your brain waves through anEEGtest, eye movements through anEOG (electrooculogram) test, and muscle movements through anEMG (nerve and muscle) testand heart through anECG (electrocardiogram)via electrodes attached to your body. We also monitor breathing and oxygen levels using various devices. In this way, we are able to determine sleep stages, heart rhythm, leg kicking and breathing problems, as well as body position, snoring and the percentage of oxygen in your blood.

Your physician would order an overnight sleep test as a result of:

  • Loud snoring
  • Awakening choking or gasping
  • Stopping breathing at night
  • Tiredness throughout the day or upon wakening
  • Fibromyalgia
  • Congestive heart failure
  • Long-term difficulty initiating and maintaining sleep

A sleep study is indicated for obstructive sleep apnea, sleep attacks, falling asleep inappropriately, and sleep-walking/talking or abnormal sleep behavior reported by others. However, a sleep study is not indicated for temporary periods of insomnia.

What you should know

 Before your visit

It is best to try and maintain as close to a regular routine as possible and avoid napping on the day of your test. If you have excessive daytime sleepiness, make sure that someone drives you to and from your sleep study.

Please do not wear jewellery or perfume on the day/night of your test. Do not use hair products or gel on the day of your test and avoid bringing large sums of money with you. You may take medications as normal, unless instructed otherwise by your physician.

Do not have any caffeinated products after 3 p.m. on the day of your test, including coffee and tea (decaffeinated and caffeinated), chocolate, cocoa, soda, pop and any medication or supplements that may have caffeine.

Please arrive at 8:30 p.m. for your overnight test. Please bring your health card and your requisition (if required).

Please bring the following items with you to your overnight sleep study:
  • Robe
  • Two-piece pajamas
  • Slippers
  • Personal hygiene items (toothbrush, toothpaste, etc.) 
  • Favorite pillow (if needed, they are supplied by the lab)
  • Medications (continue taking them as usual)

Activities to help you relax, for example:

  • Books/magazines
  • Knitting/needlepoint
  • MP3 player
  • Puzzles/crosswords


  • Snacks. If you have diabetes please ensure you bring appropriate snacks or drinks that you might require to your appointment.
  • Your Continuous Positive Airway Pressure (CPAP) unit, if you use one.
During your visit

When you arrive for your study, our technologist will show you to your room, where you will be asked to change into your night clothes and fill in pre-sleep questionnaires. The technologist will then explain the procedure and answer any questions. We will attach you to various types of equipment and then you will be able to relax until bedtime. When you are ready for bed, the technologist will connect the equipment to the monitoring devices. At this point, the equipment will be calibrated and the lights turned out.

The sleep study itself will not begin until approximately 10 to 10:30 p.m. It will last until approximately 6 a.m.

There are no side effects for this test.

 After your visit

When the test is complete, our technologist will call your name to awaken you, and will then remove the equipment. You will be free to go when you have filled in the post-sleep questionnaires. If you need to be awakened before 6 a.m., please advise the technologist. Most patients are ready to leave at 6:30 a.m.

 Care providers

Sleep disorder testing and studies are performed by a registered polysomnography technologist (RPSgT). All studies are interpreted by the sleep specialist and reports are sent to your physician.

Frequently Asked Questions

What do I do if I need assistance during my sleep study?

The technologist has visual and audio connections to each room. Therefore, we can see and hear you once the test has begun. Simply call out and the technologist will provide you with anything that you need, such as a bathroom visit, extra pillows or blankets. Should you need to get up throughout the study, simply call the technologist for assistance.

Do I need a referral to come to the sleep lab at the Centre for Respiratory Health?

Yes, please speak with your physician to be referred to the sleep lab.

Do I have to go to bed right away?

No, lab policy is to have lights out by 11:00 p.m. Once the wires are attached, you may read and relax until you are ready for bed.

Can I get up to go to the bathroom?

Yes, simply call out to the technologist who will disconnect you from the monitoring devices.

Is the technologist here all night?

Yes, the technologist monitors you throughout the entire test.

Can I get an electric shock?

No, the electrodes attached to your body do not provide any electrical currents. They measure the electrical changes at the surface of your skin. You are protected from external currents via the ground wire. All equipment used within the sleep lab adheres to the strict Canadian Electrical Standards.

Can you tell me what I am dreaming?

No, sleep medicine can only determine what stage of sleep you are in, not what your brain is thinking at the time.

Do people actually sleep with all this stuff on?

Yes, most people referred to a sleep lab are tired. Sleep onset may be delayed, but most people have no problem sleeping.

What if I don't sleep?

In this case, both your family doctor and the sleep specialist will determine if and when a repeat study will be performed. However, this rarely happens.

Do I have to sleep on my back?

No, once the lights are out you are free to get into a comfortable position. The technologist may ask you to turn on to your back later in the night. However, if for any reason you cannot sleep on your back, simply inform the technologist.