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October 2020 |  Reviewed by:  Rafael Sepulveda, MD and Andrea Matsumura, MD

What is the Maintenance of Wakefulness Test?

The Maintenance of Wakefulness Test (MWT) is used to measure how alert you are during the day. It shows whether you can stay awake for a defined period of time. The test is based on the idea that, in some cases, your ability to stay awake may be more important than how fast you fall asleep. This is an indicator of how well you can function and remain alert in quiet times of inactivity.

The test is performed in a dark room that is quiet. The test isolates you from outside factors that can influence your ability to fall asleep. These factors include such things as the following:

  • Temperature (too hot or too cold)
  • Light
  • Noise
  • Activity

After starting treatment for a sleep disorder, the MWT is used to see how well you can stay awake and function in daily activities. It is also used to help judge whether a person is too sleepy to drive or perform other daily tasks. This is critical when your job involves public transportation or safety. The results of the test will be only one factor used to assess the potential risk of a work-related accident.

There is little evidence to show how accurate the test is when children take it.

How to prepare for the Maintenance of Wakefulness Test?

Before the MWT, the sleep doctor will need to know what medications or substances you take. You may be asked to stop taking certain drugs and substances prior to the test. Further, you may be asked to take a drug test the morning of the MWT. It will help show that the results of the MWT are accurate.

The following factors may affect the study:

  • Anxiety
  • Tension
  • Depression
  • Age
  • Caffeine
  • Drugs and medications
  • Amount of sleep prior to the study

You may need to refrain from having any of the following substances before or during the test:

  • Tobacco
  • Caffeine
  • Alcohol
  • Certain medications

What is the Maintenance of Wakefulness Testing process?

The MWT consists of four sleep trials with breaks of two hours. Sometimes you will also do a sleep study the night before the MWT. It is vital that you get a normal amount and q