How It Is Done
Sleep studies are usually scheduled for evening and night hours (10 p.m. to 6 a.m.) in a special sleep lab. But if you usually sleep during the day, your test will be done during the hours you normally sleep. You'll be in a private room, much like a hotel room. For portable sleep monitoring, you'll use equipment at home that records information about you while you sleep.
You'll need to be at the sleep lab before the test so the technician can prepare you for the study. You may fill out a form about your sleep the night before. You may also be asked to fill out another form after the study about your sleep during the study.
After the test, you can shower and shampoo your hair to remove the glue from your body. Hair conditioner may help get the glue out of your hair.
For a polysomnogram (PSG) study, small pads or patches called electrodes will be placed on your head and body with a small amount of glue and tape. (The glue washes off easily after the test.) The electrodes record your brain activity, eye movement, oxygen and carbon dioxide blood levels, heart rate and rhythm, breathing rate and rhythm, the flow of air through your mouth and nose, the amount of snoring, body muscle movements, and chest and belly movements.
Soft elastic belts will be placed around your chest and belly to measure your breathing. Your blood oxygen levels will be checked by a small clip (oximeter) placed either on the tip of your index finger or on your earlobe.
The electrodes, elastic belts, and oximeter are designed to be as comfortable as possible. They should not make it hard to sleep. At the start of the test, you will be asked to do things such as blink your eyes, move your legs, and hold your breath. This is done to make sure the equipment is working as it should. Polysomnogram recording equipment and video monitors will record your movements and activities while you sleep. The technician will be in a separate room checking the recordings.
There are different ways the test may be done. You may sleep all night while the equipment records your sleep information. Or you may be monitored for half the night and then if you have sleep apnea, you may wear a mask that's connected to a continuous positive airway pressure (CPAP) machine. The mask fits over your nose or over your nose and mouth. The mask over the nose is used most often. The CPAP machine delivers air or extra oxygen. This increases the air pressure in your throat so your airway is more open when you breathe in.
When you're ready and the equipment is working right, the lights will be turned off, and you can go to sleep. For most polysomnogram studies, you will need to spend at least 6 hours overnight in the sleep lab.
Portable sleep monitoring
If you will have portable sleep monitoring, your doctor will explain how to use the monitoring equipment at home. You'll need to sleep with short tubes in your nose and a cap on your finger that connect to a small monitor. The monitor records information while you sleep, such as your breathing pattern and blood oxygen level. You may also wear a device that records sounds you make and your movements while you sleep.
Multiple sleep latency test
If a multiple sleep latency test (MSLT) is being done, you'll need to stay at the sleep lab overnight and part of the next day. During this test, you will take naps every 2 hours starting the morning after your nighttime sleep test. You will be given 20 minutes to fall asleep. If you take a nap, you'll be woken up after 15 minutes. Between naps, you try to stay awake. The amount of time it takes for you to fall asleep for the naps and the sleep patterns during the naps will be recorded using most of the same equipment used during the polysomnographic studies.
Maintenance of wakefulness test (MWT)
If an MWT is done, you'll need to stay at the sleep lab overnight and part of the next day. You will try to stay awake without napping during the day. The information will be recorded with most of the same equipment used during the polysomnographic study.
How long the test takes
- You will stay in the sleep lab overnight. For some tests, you will also stay part of the next day.