Glossary

Maintenance of Wakefulness Test [MWT]

The Maintenance of Wakefulness Test (MWT) is a sleep study (polysomnography) that measures your likelihood of falling asleep when you’re trying to stay awake during the day. You recline in bed in a dark, quiet, comfortable room and try to stay awake during 4 measurement sessions that start at about 9 or 10 a.m. and last 40 minutes each.

If you fall asleep, you’re only allowed to sleep for 90 seconds. A sleep tech will then wake you up and keep you awake until the next measurement session. If you don’t fall asleep within 40 minutes, that measurement session ends. The measurement sessions are usually every 2 hours. Most people without sleep problems are able to stay awake for at least the first 8 minutes of each measurement session.