Sleep Study - Diagnostic
Doctors call a sleep study a polysomnography. It is a sleep study in which measurements are used to identify different sleep stages and classify various sleep problems. During the study, the activities that go on in your body during sleep (brain waves, muscle movements, eye movements, breathing through your mouth and nose, snoring, heart rate and leg movements) are monitored by small metal discs (electrodes) applied to your head and skin with an adhesive. Flexible elastic belts placed around your chest and abdomen measure your breathing. The level of oxygen in your blood and your heart rate are monitored by a clip placed on your index finger or earlobe. As you sleep, you may also be videotaped for later review of any abnormalities observed during the study. A sleep technician will let you know if this is done.The test is used to:
In order to fully understand your sleep and any problems with it, it is necessary to look at various brain activities and body systems and their relationships throughout the night. A polysomnogram is often used in the following cases:
- To look for sleep-related breathing disorders, such as sleep apnea
- To set the correct levels of continuous positive airway pressure (CPAP) in patients with sleep related breathing disorders
- 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
- To help those with a history of snoring, high blood pressure, diabetes, obesity, stroke, heart conditions, insomnia, excessive daytime sleepiness
Your doctor will want to order a polysomnogram if he or she thinks you have any of these problems. You might also have a sleep study if you are already being treated for a sleep disorder, but you are not getting better. The sleep study can help your doctor see why the treatment is not working.
Preparing for the test
When many people enter a sleep center, they expect the room to be cold, bright and impersonal. However, at most sleep centers, the surroundings are homey and comfortable like a hotel room. The technical equipment and technicians will be in a room separate from your sleeping room, and the electrode wires will be gathered in a kind of ponytail behind your head so that you will be able to roll over and change positions almost as easily as you would at home.
On the day of the sleep study, it is important to avoid caffeine (coffee, tea, cola and chocolate) after 2:00 p.m., and try not to nap. Before coming to the sleep center, wash and dry your hair, and do not apply hair sprays, oils or gels.
Before coming to the center, you should pack an overnight bag as you would for an overnight stay at a hotel or a friend's house. You may wish to include your own pillow and some extra clothing. If you have special needs, advise the sleep center personnel so they can accommodate you.
It is important for your sleep professional to know if you are taking any prescribed or over-the -counter medications, since some of these can affect sleep and the interpretation of the sleep study. Sometimes certain medications need to be discontinued gradually prior to a sleep study so that the results can be correctly interpreted. However, do not discontinue any prescription medication without first consulting with your health care provider.
What to expect during the test
You will be asked to come to the sleep center in the evening. The technologists at the sleep center will go out of their way to make you feel relaxed. Some time will be given for you to make yourself at home in the sleep center bedroom. No other patients will be in the room with you; every patient has their own room.
You will not feel any pain during the polysomnogram. Sensors are gently placed on your skin and connected to a small box called a jackbox. This jackbox is then connected to a single cable that runs to a computer that receives tiny electrical signals that show when you are asleep and awake during the night and allow your breathing and vitals to be monitored. The wires are long enough to let you move around and turn over in bed. While the electrodes may feel strange on your skin at first, most people do not find them uncomfortable or an obstacle to falling asleep. The sleep specialist is aware that your sleep at the center may not be exactly like your sleep at home. This is taken into consideration and usually does not interfere with obtaining the necessary information.
The head and face sensors are brain-wave and eye-movement detectors that show when you are in REM sleep. This stands for “rapid eye movement” sleep. This is a deep stage of sleep where your eyes roll/move back and forth, and your brain waves are very active. It is also the stage of sleep when you have most of your dreams.
The sensor placed on your neck is used to detect snoring, and the sensors on your chest are used to detect your heart rate and rhythm.
The leg sensors show both minor muscle twitches and major movements that occur during the night.
Two respiratory belts and two breathing sensors will also be applied. The belts will be placed around your chest and abdomen and are used to monitor the amount of effort that is put into breathing.
Breathing sensors will be placed under your nose. The breathing monitors show the number of times you stop breathing. They can also detect low air flow and minor changes in breathing levels.
The sensor placed on your finger is used to note changes in your oxygen levels. This is called a pulse-ox and it measures the level of oxygen in your blood.
The technologists will need to make sure the sensors are working by performing some bio-calibrations. You will be asked to move your eyes, clench your teeth, do some breathing exercises, and move your legs during these calibrations. Each of these are performed for about 10-30 seconds.
You are free to read or watch TV to relax. The lights will then be turned off and it will be time for you to try to fall asleep. A low-light video camera allows a technologist to see you and hear you from a nearby tech room. He or she will have to enter your room anytime a sensor falls off or becomes loose. If you need to use the bathroom during the night you will need to call out to the technologist. He or she will come in and disconnect you from the jackbox, so you can get out of bed.
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 of the test unless no sleep is observed. 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 bio-calibrations will be performed again to test the sensors, 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 and the wax that is used to apply the electrodes to your head will need to be washed out with shampoo. Otherwise, you can return to normal activities on the day after a sleep study.
What to expect after the test
A technologist is the first one to look over the data from a sleep study. First, he or she will chart your sleep stages. Then, he or she will look for any events of abnormal breathing or leg movement. The results of the sleep study are reviewed by a board-certified sleep doctor. The doctor will review the study to find out what kind of sleep problem you may have and treatment recommendations will be made if evidence of a sleep disorder is found.
It usually takes about a week to get the results of a sleep study. At times, the doctor who takes a look at the study needs to get more information. He or she may talk to the technologist or to the doctor who sent you to the sleep center.
Sleep study results are not generally discussed over the telephone because of their complex nature. Therefore, to fully understand the results of your sleep study, what they mean and any recommendations that are made, you should meet with your health care provider face-to-face. The provider that ordered the study will receive the results. If you are diagnosed with a sleep related breathing disorder the doctor will usually recommend another study to be done while using therapy. The type of therapy required during this second study will also be discussed during your results.