The Maintenance of Wakefulness Test (MWT) is used to measure whether you are able to stay awake during a defined period of time. This is an indicator of how well you are able to function and remain alert in quiet times of inactivity. The test is also used to help judge whether a patient is too tired to drive or perform other daily tasks.
The test isolates you from outside factors that can influence your ability to fall asleep.
- Temperature (too hot or too cold)
- 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:
- Medications as instructed by your physician
The sleep specialist will help you decide what you can and cannot have. You may be asked to take a test to screen for drugs on the morning of the MWT. It will help show that the results of the MWT are accurate.
Who is tested?
The MWT is used to see if someone with a sleep disorder is responding well to treatment. Results of multiple tests may be compared over a period of time. This can show if treatment is helping a patient overcome sleepiness.
The MWT may be used to evaluate how well a person with a sleep disorder is able to stay awake. This is critical when the person’s 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 given to children.
How is the study performed?
All sunlight will be kept out of your room during trials. The room will be dimly lit. Outside factors that might affect your sleep are limited. The room temperature is set at your personal comfort level.
The MWT consists of four sleep trials with breaks lasting for two hours in between them. Sometimes you will also do an overnight 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, your test may need to be moved to another day.
The first sleep trial is performed between an hour and a half and three hours after your normal wake-up time. This usually means that you will start around 9 a.m. or 10 a.m. A light breakfast will be provided.
Sensors are placed on your head, face and chin. They send tiny 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.
For each trial, you will sit quietly in a recliner. 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 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 light lunch will be provided.
A total of 97.5 percent 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 from 40 to 59 percent of people with normal sleep stay awake for the entire 40 minutes of all four trials.
Who reads the test?
A technologist is the first one to look over the data from the test. He or she will chart your wake-sleep times. The results will be given to a doctor. The MWT is not a test that you can fail. The doctor will simply review the study to assess your level of daytime sleepiness.
How do I get the results?
It usually takes about two weeks to get the results of a MWT. At times the doctor who takes a look at the test needs to get more information. He or she may talk to the technologist or to the doctor who sent you to the center.
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 him or her. Please call to schedule a follow-up appointment with the physician who ordered the study, unless otherwise indicated.