The multiple sleep latency test (MSLT) is a diagnostic tool which tests for excessive daytime sleepiness. This test is used when medical providers are concerned with the amount of adequate and quality sleep a patient is receiving. During this test you are given 5 opportunities to nap every two hours during normal wake times. You will then be measured to see how fast you fall asleep in each nap (sleep latency) and how quickly REM sleep begins. A positive MSLT is obtained when you fall asleep with a mean sleep latency below 8 minutes and had at least no more than one nap where REM sleep was reached.