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 quality of sleep the night before the test. If this does not happen, then your test may need to be moved to another day.

Sensors are placed on your head, face and chin. They send electrical signals to a computer. The signals show when you are asleep and awake during the test. You will not feel any pain during the MWT. The sensors are gently placed on your skin and connected to a computer. The cables are long enough to let you move around in the bed.

You will be asked to move your eyes, clench your teeth and turn your head. This will make sure that the sensors are working properly prior to starting 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. It is important that you are as comfortable as you can be. You will be asked to sit still and look directly ahead of you. Then you simply try to stay awake for as long as you can.

You are not allowed to do other things to try and keep yourself awake. This includes actions such as singing or slapping your face.

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.

Between trials, you will have to stay out of bed and occupy yourself so that you remain awake.

A total of 97.5% of normal sleepers stay awake for an average of eight minutes or more during the MWT. Falling asleep in an average of less than eight minutes during the test would be considered abnormal. Results show that 40% to 59% of people with normal sleep stay awake for the entire 40 minutes of all four trials.

After the last nap trial, you will test the sensors again, and then they will be removed. This will complete the study, and you will be free to go.

How are the Maintenance of Wakefulness Test results scored?

It takes about two weeks to get the results of your MWT. A sleep technologist is the first one to look over the data from the test. She will chart your wake-sleep times. The results will be given to a doctor to assess your level of daytime sleepiness.

The doctor who ordered the study will discuss the results with you. If your primary care doctor ordered it, then the results are sent to her. If you met with a doctor in the sleep center, then she will tell you the results.