Medical Terminology

Maintenance of Wakefulness Test (MWT)

« Back to Glossary Index

The purpose of the Maintenance of Wakefulness Test (MWT) is to see if you are able to stay awake during the daytime. The MWT takes place in a darkened, quiet, comfortable room. A technician places sensors on your head, face, and neck that can measure sleep. You recline in bed and try to stay awake during each of four measurement periods. The four measurement periods start about 9 or 10 am and last 40 minutes each. If you fall asleep, you are allowed to sleep for 90 seconds and are then awakened and kept awake until the next measurement period. If you don’t fall asleep within 40 minutes, that measurement period is ended. The measurement periods typically take place every two hours. This test is similar to the Multiple Sleep Latency Test (MSLT), but the MWT measures your likelihood of falling asleep when you are trying to stay awake. This is a subtle but important difference. Most people without sleep problems are able to stay awake for at least the first 8 minutes of each measurement period.