Sleep Studies



  • Overnight Sleep Study
  • Split Night Sleep Study
  • CPAP Titration Study
  • Nap Studies (MSLT and MWT)

Overnight Sleep Study or Polysomnogram

Overnight Sleep Study
A polysomnogram is a painless test that records your brain waves, heart beat, and breathing as you sleep. It also records your eye and leg movements as well as muscle tension. Sensors are placed on your head, face, chest and legs. They send tiny electrical signals to a computer. The recording of brain waves and eye movements allow the sleep technologists and sleep physicians to stage the depth of your sleep and detect REM (rapid eye movement) sleep. There are no needles involved in polysomnography or sleep studies.

Overnight Sleep Study or Polysomnogram

The breathing monitors detect reduction or complete cessation of air flow and changes in oxygen levels so that the diagnosis and the severity of sleep apnea can be established. Oxygen levels are monitored by a comfortable finger clip to note changes in the level of oxygen in your blood.

The leg sensors show both minor twitches and major movements that occur during the night.

Who gets it?
A polysomnogram or an overnight sleep study is recommended in the following cases:

  • To establish the diagnosis of obstructive sleep apnea or other forms of sleep breathing disorders such as central sleep apnea or sleep hypoventilation.
  • To set the correct levels of positive airway pressure therapy to correct the abnormal breathing during sleep. The two most common forms of positive airway pressure therapy are continuous positive airway pressure (CPAP) or bi-level positive airway pressure (bi-level PAP). CPAP and bi-level PAP are devices that generate flow and the pressure generated maintains upper airway patency to relieve apneas, shallow breathing, and snoring.
  • To go along with a daytime nap study to see if someone has narcolepsy.
  • To look for behaviors during sleep that can be violent or could be harmful to the patient or others.

Your physician may order a sleep study or polysomnogram to rule out or treat sleep apnea or to assess why you may not be getting better after treatment for your sleep disorder. Sleep studies are also performed to evaluate unusual sleep movements or behaviors, narcolepsy or excessive daytime sleepiness.

What happens when I am scheduled for a sleep study?
The staff at the sleep disorders center and sleep laboratory will go out of their way to make you feel relaxed. You will be asked to come to the center in the evening. You will be in a private room with private bathroom, shower and TV. Some time will be given for you to make yourself at home in the bedroom. No other patients will be in the room with you.

You will not feel any pain during the polysomnogram. The sleep technologist gently applies the sensors on your skin and connects them to a computer. The wires are long enough to let you move around and turn over in bed. For purposes of calibration at the beginning of the study you will be asked to move your eyes, clench your teeth and move your legs. This will make sure that the sensors are working. All the wires are connected to one main cable so that if you need to use the washroom, the sleep technologist can simply disconnect the main cable and allow you to use the washroom. Upon returning from the washroom, the main cable will get reconnected.

You are free to read or watch TV. At some point during the night you will be informed by the sleep technologist that the lights and TV will be turned out and it is time for you to try to fall asleep. A low-light video camera allows a technologist to see you from a nearby room. He or she will have to enter your room only if a sensor comes loose or you request their assistance.

The sleep study or polysomnogram is not a test that you can fail. Nearly everyone falls asleep during the study. Most people do not sleep as well as they do at home. This will not affect the results. In most cases, you do not need to sleep for a full eight hours to find the source of your problem.

In the morning the sleep technologists will test the sensors again, and then they will be removed. This will complete the study, and you will be free to go. You may be tired if you did not sleep well during the night. Otherwise, you can return to normal activities on the day after a sleep study.

Who reads it?
A sleep technologist reviews the record and the data from a sleep study. First, he or she will chart your sleep stages and any abnormal breathing or leg movement. The results will be given to a board-certified sleep specialist who will review the study to find out what kind of sleep problem you may have.

How do I get the results?
It usually takes about 3-4 days for the sleep center staff to get the results of a sleep study sent to your physician. The doctor who ordered the study will discuss the results with you. If you were seen by a sleep specialist at our sleep center and the sleep specialist ordered the sleep study, then he or she will tell you the results.


Split Night Sleep Study or or Split Night Polysomnogram

Split night sleep study

A polysomnogram is a painless test that records your brain waves, heart beat, and breathing as you sleep. It also records your eye and leg movements as well as muscle tension. Sensors are placed on your head, face, chest and legs. They send tiny electrical signals to a computer. The recording of brain waves and eye movements allow the sleep technologists and sleep physicians to stage the depth of your sleep and detect REM (rapid eye movement) sleep. There are no needles involved in polysomnography or sleep studies.

The breathing monitors detect reduction or complete cessation of air flow and changes in oxygen levels so that the diagnosis and the severity of sleep apnea can be established. Oxygen levels are monitored by a comfortable finger clip to note changes in the level of oxygen in your blood.

The leg sensors show both minor twitches and major movements that occur during the night.

Why is it called split night?
You doctor may order a split night study. This means that if during the sleep study the sleep technologist detects significant sleep apnea, then treatment with positive airway pressure may be started in the second portion of the night. The study is called split night because the first half of the night is the diagnostic portion and the second half of the night is the treatment portion of the sleep study. However, frequently the doctors order a split night sleep study because of suspicion of sleep apnea but if the sleep study shows that the sleep apnea is fairly mild, then CPAP treatment may not be performed on the same night. The doctor may wait to review the results of the entire night of the sleep study. Then he or she will decide if you need to come in for a second sleep study. The second study is called CPAP or positive airway pressure titration study.

What happens if I do have significant sleep apnea and treatment is initiated the same night?
At the beginning of the night the sleep technologists will show you a variety of masks so that you can choose the most comfortable one with the best fit. This way, during the second portion of the night when CPAP therapy needs to be initiated, the mask will be connected by a tube to a small electric unit which is a flow generator. The unit has a fan that pushes air through the tube. The mask allows the air to gently blow into the back of your throat to maintain you upper airway open so that you can breathe normally. The two most common forms of positive airway pressure therapy are continuous positive airway pressure (CPAP) or bi-level positive airway pressure (bi-level PAP).

Pressure is started at a very low level. It is then increased at various intervals during the night. The goal is to find the right level of air pressure that will prevent the collapse of your upper airway and to correct the oxygen levels. This eliminates pauses in your breathing and snoring as you sleep.

Who gets it?

Split night sleep study with CPAP
A split night polysomnogram or split night sleep study is recommended in the following case:

  • To establish the diagnosis of obstructive sleep apnea or other forms of sleep breathing disorders such as central sleep apnea or sleep hypoventilation and if significant sleep apnea is detected to set the correct levels of positive airway pressure therapy to correct the abnormal breathing during sleep. The two most common forms of positive airway pressure therapy are continuous positive airway pressure (CPAP) or bi-level positive airway pressure (bi-level PAP). CPAP and bi-level PAP are devices that generate flow and the pressure generated maintains upper airway patency to relieve apneas, shallow breathing, and snoring.

What happens when I am scheduled for a split night sleep study?
The staff at the sleep disorders center and sleep laboratory will go out of their way to make you feel relaxed. You will be asked to come to the center in the evening. You will be in a private room with private bathroom, shower and TV. Some time will be given for you to make yourself at home in the bedroom. No other patients will be in the room with you.

You will not feel any pain during the polysomnogram. The sleep technologist gently applies the sensors on your skin and connects them to a computer. The wires are long enough to let you move around and turn over in bed. For purposes of calibration at the beginning of the study you will be asked to move your eyes, clench your teeth and move your legs. This will make sure that the sensors are working. All the wires are connected to one main cable so that if you need to use the washroom, the sleep technologist can simply disconnect the main cable and allow you to use the washroom. Upon returning from the washroom, the main cable will get reconnected.

You are free to read or watch TV. At some point during the night you will be informed by the sleep technologist that the lights and TV will be turned out and it is time for you to try to fall asleep. A low-light video camera allows a technologist to see you from a nearby room. He or she will have to enter your room only if a sensor comes loose or you request their assistance. The CPAP pressure is remotely adjusted by the sleep technologists.

The split night sleep study or split night polysomnogram is not a test that you can fail. Nearly everyone falls asleep during the study. Most people do not sleep as well as they do at home. This will not affect the results. In most cases, you do not need to sleep for a full eight hours to find the source of your problem. If the sleep study shows that the sleep apnea is fairly mild or if there is not enough time to start treatment, then the CPAP treatment may not be performed on the same night. The doctor may wait to review the results of the entire night of the sleep study. Then he or she will decide if you need to come in for a second sleep study. The second study is called CPAP or positive airway pressure titration study.

In the morning the sleep technologist will test the sensors again, and then they will be removed. This will complete the study, and you will be free to go. You may be tired if you did not sleep well during the night. Otherwise, you can return to normal activities on the day after a sleep study.

Who reads it?
A sleep technologist reviews the record and the data from a sleep study. First, he or she will chart your sleep stages and any abnormal breathing or leg movement. The results will be given to a board-certified sleep specialist who will review the study to find out what kind of sleep problem you may have.

How do I get the results?
It usually takes about 3-4 days for the sleep center staff to get the results of a sleep study sent to your physician. The doctor who ordered the study will discuss the results with you. If you were seen by a sleep specialist at our sleep center and the sleep specialist ordered the sleep study, then he or she will tell you the results.

If a split night sleep study was ordered but it could not be performed and the sleep doctors think you need to return for a second study (also called a CPAP or positive airway pressure titration study) then the sleep center staff can schedule you for the second night in the laboratory. Alternatively, the original referring physician who ordered the split night sleep study can order a CPAP or positive airway pressure titration study after reviewing the results of the initial overnight sleep study.

Expedited CPAP Care Program:
If you are diagnosed with sleep apnea and it was successfully treated with CPAP during the split night sleep study, you may be eligible for Expedited CPAP Care Program. However, Expedited CPAP Care Program needs to be ordered by your physician when the sleep study is scheduled.

If ordered by your physician, Expedited CPAP Care can save you time while optimizing your care with CPAP therapy. In line with our mission to deliver the best service, should you be diagnosed with sleep apnea, we will help set up the CPAP therapy before you leave the sleep center. With Expedited CPAP Care, you will be seen by a sleep specialist approximately 31– 45 days after being treated with CPAP to address any problems you may have with the device.


CPAP or positive airway pressure titration study

CPAP or positive airway pressure titration study

A CPAP or positive airway pressure titration study is performed on someone who has already been diagnosed with sleep apnea or a sleep related breathing disorder by an overnight sleep study or polysomnogram. The two most common forms of positive airway pressure therapy are continuous positive airway pressure (CPAP) or bi-level positive airway pressure (bi-level PAP). CPAP is currently the best treatment for sleep apnea.

At the beginning of the night the sleep technologists will show you a variety of masks so that you can choose the most comfortable one with the best fit. The mask will be connected by a tube to a small electric unit which is a flow generator. The unit has a fan that pushes air through the tube. The mask allows the air to gently blow into the back of your throat to maintain you upper airway open so that you can breathe normally. Pressure is started at a very low level. It is then increased at various intervals during the night. The goal is to find the right level of air pressure that will prevent the collapse of your upper airway and to correct the oxygen levels. This eliminates pauses in your breathing and snoring as you sleep.

Similar to an overnight sleep study or polysomnogram, sensors are placed on your head, face, chest and legs. They send tiny electrical signals to a computer. The recording of brain waves and eye movements allow the sleep technologists and sleep physicians to stage the depth of your sleep and detect REM (rapid eye movement) sleep. There are no needles involved in CPAP or positive airway pressure titration study.

The mask that is placed on your nose (or nose and mouth) can detect air flow and whether there is any evidence of upper airway narrowing and collapse. Additionally, oxygen levels are monitored by a comfortable finger clip to note changes in the level of oxygen in your blood.

Who gets it?
A CPAP or positive airway pressure titration study is recommended in the following case:

  • To adequately treat sleep apnea or sleep related breathing disorder in a patient with a established diagnosis of obstructive sleep apnea or other forms of sleep breathing disorders such as central sleep apnea or sleep hypoventilation. Therefore, a prior overnight sleep study or polysomnogram is necessary for the sleep center to perform a CPAP titration study.

What happens when I am scheduled for a CPAP or positive airway pressure titration study?
The staff at the sleep disorders center and sleep laboratory will go out of their way to make you feel relaxed. You will be asked to come to the center in the evening. You will be in a private room with private bathroom, shower and TV. Some time will be given for you to make yourself at home in the bedroom. No other patients will be in the room with you.

You will not feel any pain during the study. The sleep technologist gently applies the sensors on your skin and connects them to a computer. The wires are long enough to let you move around and turn over in bed. You will be asked to move your eyes, clench your teeth and move your legs. This will make sure that the sensors are working. All the wires are connected to one main cable so that if you need to use the washroom, the sleep technologist can simply disconnect the main cable and allow you to use the washroom. Upon returning from the washroom, the main cable will get reconnected.

You are free to read or watch TV. At some point during the night you will be informed by the sleep technologist that the lights and TV will be turned out and it is time for you to try to fall asleep. A low-light video camera allows a technologist to see you from a nearby room. He or she will have to enter your room only if a sensor comes loose or you request their assistance. The CPAP pressure is remotely adjusted by the sleep technologists.

The CPAP study is not a test that you can fail. Nearly everyone falls asleep during the study. Most people do not sleep as well as they do at home. This will not affect the results. In most cases, you do not need to sleep for a full eight hours to find the source of your problem. During the study CPAP (or other forms of positive airway pressure therapy) is titrated so that your breathing and oxygen levels become normal.

In the morning the sleep technologists will test the sensors again, and then they will be removed. This will complete the study, and you will be free to go. You may be tired if you did not sleep well during the night. Otherwise, you can return to normal activities on the day after a sleep study.

Who reads the CPAP study?
A sleep technologist reviews the record and the data from the CPAP titration study. First, he or she will chart your sleep stages and any abnormal breathing or leg movement. The results will be given to a board-certified sleep specialist who will review the study to determine the appropriate pressure levels required to treat your sleep apnea.

How do I get the results?
It usually takes about 3-4 days for the sleep center staff to get the results of a sleep study sent to your physician. The doctor who ordered the study will discuss the results with you. If you were seen by a sleep specialist at our sleep center and the sleep specialist ordered the sleep study, then he or she will tell you the results.

Expedited CPAP Care Program:
If you are successfully treated with CPAP during the split night sleep study, you may be eligible for Expedited CPAP Care Program. However, Expedited CPAP Care Program needs to be ordered by your physician when the CPAP titration study is scheduled.

If ordered by your physician, Expedited CPAP Care can save you time while optimizing your care with CPAP therapy. In line with our mission to deliver the best service, should you be diagnosed with sleep apnea, we will help set up the CPAP therapy before you leave the sleep center. With Expedited CPAP Care, you will be seen by a sleep specialist approximately 31– 45 days after being treated with CPAP to address any problems you may have with the device.


Nap Studies (MSLT and MWT)

There are two types of nap studies: Multiple Sleep Latency Test (MSLT) and Maintenance of Wakefulness Test (MWT).

MSLT is used to see how quickly you fall asleep in quiet situations during the day. This test is the standard way to objectively measure your level of daytime sleepiness. In contrast, the MWT is used to measure how alert you are during the day and it shows whether or not you are able to stay awake for a defined period of time. This is an indicator of how well you are able to function and remain alert in quiet times of inactivity.

Both MSLT and MWT are painless tests that record your brain waves, eye movements as well as muscle tension. Sensors are placed on your head and face. The sleep technologist gently applies the sensors on your skin and connects them to a computer. The wires are long enough to let you move around and turn over in bed. For purposes of calibration at the beginning of each nap you will be asked to move your eyes, open and close your eyes, and move your head. This will make sure that the sensors are working. All the wires are connected to one main cable so that if you need to use the washroom, the sleep technologist can simply disconnect the main cable and allow you to use the washroom. Upon returning from the washroom, the main cable will get reconnected. They send tiny electrical signals to a computer. The recording of brain waves and eye movements allow the sleep technologists and sleep physicians to stage the depth of your sleep and detect REM (rapid eye movement) sleep. There are no needles involved in nap studies.

Sleep Technician

The MSLT is always preceded by an overnight sleep study in the laboratory. This means that you arrive at the Sleep Disorders Center the night before the nap studies. The first nap trial begins between 1.5 and three hours after your usual wake up time. The MSLT consists of five 20 minute nap opportunities with breaks lasting for two hours in between them. A shorter four-nap study may also be used but the five-nap version is more reliable at detecting narcolepsy. You will be allowed to have a light breakfast at least one hour before the first MSLT nap trial and lunch at least one hour before initiating the noon or early afternoon MSLT nap trial. Results of the MSLT nap study are routinely used to detect sleep disorders. For each MSLT nap trial, you are asked to lie quietly in bed and try to go to sleep. Then the lights are turned off. Once the lights are out, the test will measure how long it takes you to fall asleep. After sleeping for 15 minutes, you will be awakened. Each MSLT nap trial will end if you do not fall asleep within 20 minutes. Between MSLT nap trials, you will have to stay out of bed and occupy yourself so that you remain awake. After the last MSLT nap trial, the sleep technologist will test the sensors again, and then they will be removed. This will complete the study, and you will be free to go. The stimulants and certain other medications need to be stopped for two weeks before the MSLT. Your sleep specialist should help you properly schedule the use of any other medications and make the final decision as to which medications can be continued.

The MWT however, is not preceded by an overnight sleep study. Patients are asked to report to the sleep disorders center within one to one and a half hour after their usual wake time. The first MWT sleep trial is performed between 1.5 and three hours after your normal wake-up time. This usually means that you will start around 9 a.m. or 10 a.m. You should have a light breakfast at least one hour before the first trial. Upon arrival to the sleep disorders center the sleep technologist will apply the sensors on your head and face. These sensors send tiny electrical signals to a computer in order to record brain waves and eye movements to allow us to stage the depth of your sleep and detect REM (rapid eye movement) sleep. You will be asked to move your eyes, clench your teeth and turn your head. This will make sure that the sensors are working. A low-light video camera allows a technologist to see you from a nearby room.

The MWT consists of five 40 minute trials with breaks lasting for two hours in between. During each MWT trial you will sit quietly in bed with your back and head supported by a pillow. It is important that you are as comfortable as you can be. You will be asked to sit still and look directly ahead of you. Then you simply try to stay awake for as long as you can. You are not allowed to do other things to try and keep yourself awake. This includes actions such as singing or slapping your face. If you fall asleep, then you will be awakened after sleeping for only about 90 seconds. The test will end if you do not fall asleep within 40 minutes. Between MWT trials, you will have to stay out of bed and occupy yourself so that you remain awake.

Who gets an MSLT?
The MSLT is the standard tool used to evaluate people who are thought to have narcolepsy. Most people with narcolepsy fall asleep in an average of less than five minutes during the MSLT nap trials. Some take longer than five minutes to fall asleep. There are also people without narcolepsy who fall asleep in less than five minutes.

The MSLT also counts sleep-onset REM periods (SOREMPS). This is when you enter REM sleep very soon after you fall asleep. REM sleep is normally the fifth and last stage of each sleep cycle. It usually begins about 90 minutes after you fall asleep. People with narcolepsy often have two or more SOREMPS in a nap trial.

The MSLT may be used to see if a person has idiopathic hypersomnia. Patients with idiopathic hypersomnia fall asleep easily but do not have SOREMPS.

The MSLT reveals a broad range of time in which it takes normal sleepers to fall asleep during the study. Normal sleepers tend to fall asleep in an average of about ten minutes or more during the five naps of the MSLT. Due to the wide range of normal times, the results from these nap trials alone are not enough to diagnose a sleep disorder. Sleep doctors must also consider other data, tests, and medical information.

What happens when I have it?
You may be asked to take a urine test to screen for drugs before the nap study. This will normally take place on the morning of the MSLT. It will help show that the nap study results are accurate. It will be helpful if you fill out a sleep diary for at least one week before the MSLT. This will allow the sleep doctor to see your normal sleep-wake pattern. Smoking should be stopped at least 30 minutes before each nap trial.

You will not be allowed to have any drinks with caffeine during the study. You will also not be able to see any bright sunlight. Outside factors that might affect your sleep are limited. Your room is made dark and quiet.

The MSLT is taken right after you do an overnight sleep study. For the MSLT to be accurate, you should have had a total sleep time of at least six hours during the overnight sleep study. The MWT does not need to be performed after an overnight sleep study.

Who reads it?
A sleep technologist reviews the record and the data from a sleep study. First, he or she will chart your sleep stages and any abnormal breathing or leg movement. The results will be given to a board-certified sleep specialist who will review the study to find out what kind of sleep problem you may have.

How do I get the results?

It usually takes about 3-4 days for the sleep center staff to get the results of a sleep study sent to your physician. The doctor who ordered the study will discuss the results with you. If you were seen by a sleep specialist at our sleep center and the sleep specialist ordered the sleep study, then he or she will tell you the results.