What Is a Maintenance of Wakefulness Test?

Excessive daytime sleepiness is a chronic issue for 5 percent of the population. It is the most common reason that people visit a sleep disorder center.

Daytime sleepiness is considered excessive if it happens in situations where you should be awake and alert. Poor sleep and increased daytime sleepiness have been associated with increased risk of other diseases and it can be dangerous to others.¹

Tests that measure sleep

There are a variety of sleep studies that can be used to examine the quality of your sleep. These are often conducted in a sleep center where a sleep technician can record data while you sleep. One of these tests is a polysomnogram and it is used to diagnose sleep disorders. A multiple sleep latency test (MSLT) looks at how quickly someone is able to fall asleep. CPAP titration studies are performed to ensure that the CPAP (continuous positive airway pressure) settings are right for each person.²

If you have had issues with your sleep or have been diagnosed with a sleep disorder like sleep apnea, your doctor may also want to order another test. The maintenance of wakefulness test (MWT) is done during the day rather than at night. It is used to see how well participants can stay awake and alert throughout the day. This can gauge how well you function during the day, particularly during quiet or inactive times.^2-3

What is the MWT used for?

Staying alert in calm, quiet conditions is very important in certain jobs and situations. Driving, whether for work or for your personal life, is particularly dangerous if you are sleepy. The MWT can help judge if you are too tired to drive or perform other tasks. This information can be used to help assess if it is safe for you to work in certain jobs.³

It is also useful to see if treatment has been effective for someone living with a sleep disorder. This sleep study can be performed multiple times over a period of time. The results can then be compared to see if symptoms are improving or if therapy should be changed.³

What should I expect during an MWT?

MWTs are performed during 1 day at a sleep center or sleep laboratory. Participants will have 4 to 5 trials where they sit in a quiet and relaxing environment for 40 minutes at a time. The room is comfortable, dimly lit, and free of stimulation. There are no windows, television, or other things that distract participants.²

Participants are asked just to sit still and look forward. They are asked not to distract themselves to stay awake. This includes talking out loud, singing, or pinching themselves. They will sit like this either until they fall asleep or until the 40 minutes has passed. This will then be repeated later that day.²

The first trial begins 90 minutes to 3 hours after the participant normally wakes up. There are 2 hours in between each trial. Breakfast and lunch are also offered. In those 2 hours, participants may eat, watch TV, read, or walk around the building. They may not go outside, however. Sunlight can affect your sleepiness so walking outside could affect the test results. Napping is also not allowed because that can alter results.²

While in the room, participants will be connected to sensors to track vital signs and movement. Heart rate and heart activity will be measured through 3 electrocardiogram (EKG) leads on the chest. Brain activity will be measured through 4 electroencephalogram (EEG) leads on the head and scalp. Eye movement and chin movement will be measured with leads on the face. This information is sent to a sleep technician in another room. It indicates when a patient falls asleep.²

How should I prepare for an MWT?

You should try to get a normal night’s sleep the day before the test. This helps to make the results more accurate. You should also dress in comfortable street clothes. You will likely be asked to avoid nicotine and caffeine before or during the test. These may keep you awake and can alter the results.² Your doctor or sleep center will give you more information and can answer any questions that you have.

If you have excessive daytime sleepiness for the first time or if you still have excessive daytime sleepiness after you have started therapy, speak to your doctor about your symptoms. You can also contact a local sleep clinic to see if a sleep study may be right for you.²