Sleep Studies: About This Test

What is it?

Sleep studies are tests that watch what happens to your body during sleep. These studies usually are done in a sleep lab. Sleep labs are often located in hospitals. Sleep studies you do at home can be done with portable equipment. But they may not give the same results as a sleep lab.

Why is this test done?

Sleep studies may be done if your sleep is not restful or if you are tired all day. These studies can help find sleep problems, such as:

• Sleep apnea.
• Excessive snoring.
• Problems staying awake, such as narcolepsy.
• Problems with nighttime behaviors. These include sleepwalking, night terrors, bed-wetting, and REM behavior disorders (RBD).
• Conditions such as periodic limb movement disorder. This is repeated muscle twitching of the feet, arms, or legs during sleep.
• Seizures that occur at night (nocturnal seizures).
• Ongoing problems that have not responded to treatment.

How do you prepare for the test?

• You may be asked to keep a sleep diary before your sleep study.
• Don't take any naps on the day of your test.
• You may be asked to avoid food or drinks with caffeine during the afternoon and evening before your test.
• If the sleep study will be done in a sleep lab, you will be asked to shower or bathe before your test. Don't use sprays, oils, or gels on your hair. Don't wear makeup, fingernail polish, or fake nails. Take a small overnight bag with personal items, such as a toothbrush, a comb, favorite pillows or blankets, and a book. You can wear your own nightclothes.
• If you will have portable sleep monitoring, your doctor will explain how to use the equipment at home.

How is the test done?

• In the sleep lab, you will be in a private room, much like a hotel room.
• Small pads or patches called electrodes will be placed on your head and body with a small amount of glue and tape. These will record things like brain activity, eye movement, oxygen levels, and snoring.
• 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.
• If you have sleep apnea, you may wear a mask that is connected to a continuous positive airway pressure (CPAP) machine.
• Depending on the type of test, you will be allowed to sleep through the night or you'll be awakened periodically and asked to stay awake for a while.
• If you use portable sleep monitoring, follow the instructions your doctor gave you.

How long does the test take?

• You will stay in the sleep lab overnight. For some tests, you will also stay part of the next day.

What happens after the test?

• You will be able to go home right away.
• You may not sleep well during the test and may be tired the next day.
• You can go back to your usual activities.
• After your sleep problem has been identified, you may need a second study if your doctor orders treatment such as CPAP.