Sleep Medicine Services
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Maintenance of Wakefulness Test: What to Expect

The Maintenance of Wakefulness Test (MWT) is a daytime sleep study that measures your ability to stay awake and alert during the day. The MWT can also tell your doctor how well your treatment is working.

Before the test

A MWT is usually done the day after a polysomnogram (PSG) and takes most of the day. You will need to refrain from tobacco and caffeine before or during the test. Your doctor will discuss any changes to your medication schedule before the test. You should have a light breakfast at least one hour before the first trial.

What to expect

You'll be placed in a quiet comfortable room at a Riverside Center for Sleep Medicine. Sunlight will be kept out of the room and the temperature will be set at your personal comfort level. The goal is to remove any outside influences on your sleepiness. The MWT consists of several sleep trials with breaks lasting for two hours in between them.

  • You'll start between 1.5 to three hours after your normal wake-up time.
  • Sensors are placed on your head, face, and chin, which will show when you are asleep or awake during the test.
  • A low-light video camera allows a technologist to see you from a nearby room.
  • For each trial, you will sit quietly in bed with your back and head supported by a pillow.
  • You will be asked to sit still and look directly ahead of you while you try to stay awake as long as you can.
  • If you fall asleep, you will be awakened after sleeping for only about 90 seconds.
  • The test will end if you do not fall asleep within 40 minutes.

Test results

A technologist will chart your wake-sleep times. A Riverside sleep specialist will review the study to assess your level of daytime sleepiness. Final results of your test may take two weeks. Your referring physician will discuss the results with you.