Maintenance of wakefulness test (MWT)


A maintenance of wakefulness test (MWT) measures if you can stay awake during the daytime under certain conditions


Our locations

London Bridge Hospital

London Bridge Hospital

27 Tooley Street SE1 2PR London

Why do I need a test foe wakefulness?

If you're in a profession where it's essential to stay alert and awake for safety — such as drivers or pilots — you may have a maintenance of wakefulness test (MWT) to assess your suitability.

MWTs may also be recommended to see how well you're responding to treatment for a sleep disorder.

Need to know

When you arrive in the morning, your consultant will attach several sensors to your head and chest using small sticky pads. If you've been in for an overnight sleep study, these sensors will already be in place. The sensors measure your brain waves, eye movement, pulse and muscle activity, and will determine if and when you fall asleep.

The test involves four sleep trials that occur at two hour intervals. During each trial, you'll sit quietly on a bed for 40 minutes with your back and head supported by a pillow. You'll be asked to look directly ahead and try to stay awake as long as you can. If you fall asleep, you'll be woken after 90 seconds.

Your consultant will explain the test to you and answer any questions you may have. They'll let you know if there is anything specific you will need to do to prepare. This may include avoiding certain medications or caffeine in the days before your test. They may also recommend avoiding smoking or heavy meals on the day of your test.
Your consultant will remove the sensors and let you know about any next steps. If you're not staying for further sleep studies, you should be able to return home when the test is over. You may need to come back for a follow-up appointment to review your results and discuss options for treatment or further assessments if needed.