The Multiple Sleep Latency Test or MSLT is a test which is used to assess sleepiness. This test is completed after a full night sleep study. This test will be comprised of 4-5 testing sessions (opportunities to nap) which will conclude between 1 and 4 pm the following day. You will be given 20 minutes to fall asleep for each nap, and naps will occur every two hours. In between naps, you will be required to stay awake. You may not leave the testing area in that time, or have caffeine.

The Maintenance of Wakefulness or MWT testing is a test used to assess wakefulness. This test does not require a full night sleep study just prior to testing, but this is left at the discretion of your ordering provider. This test will be comprised of 4 testing sessions where you will be asked to try to stay awake (without physical activity) for 40 minutes in each test sitting in a darkened room. Again, there will be two hours between wakeful opportunities. You may not leave the testing area in that time, or have caffeine. This test will conclude between 1 to 3 p.m. the following day.

You should bring with you any nutritional needs you may have. This includes bringing a breakfast, lunch and snacks between the testing sessions. There are no dietary restrictions with the exceptions of chocolate or caffeine. There is a refrigerator and microwave that can be made available to you if needed as well. You will not be allowed to leave during the testing for your safety and due to liability, so please bring enough food for the day! Leaving the testing grounds or engaging in activity that is not allowed may invalidate the testing.

Finally, for the polysomnogram (sleep study) preceding your daytime test: if you have sleep apnea already, please bring in your own mask so you can feel most comfortable during the night.


If you have been told that you can go home prior to completion of the study between 3pm to 5pm, this is due to data collected prior. The technician cannot inform you of the specifics of the cancellation. This information will be disclosed in full once all of the data has been collected and reviewed. However, some examples of why the MSLT is cancelled:

  • Insufficient total sleep time noted during the sleep study.
  • Sleep apnea noted during the night-time sleep study.
  • Sufficient data is obtained to allow an accurate diagnosis to end the test early

If you have any questions or concerns please contact the office.