hours between nap opportunities. The patient may be asked to fill out a post-test questionnaire. A sleep technologist will gently place sensors on patient's head, face and chin. These sensors are connected to a computer. The sensors show when patient is asleep and awake, and transmit data used to determine when patient is in REM sleep. The nap trial begins when the lights are turned off. Interpretation A clinical neurophysiologist, neurologist, psychiatrist or sleep specialist will review the results and inform the patient or the patient's primary care physician of the interpretation of the test result in the context of the clinical problem. The sleep latency (time between the start of the nap opportunity and sleep onset determined by EEG) is determined for each of the four or five nap opportunities. If no sleep occurred during a nap opportunity, the sleep latency is recorded as 20 minutes for that nap opportunity. The average of sleep latency from the four or five naps is taken as the overall sleep latency for the entire test. In general, a sleep latency of less than 8 minutes is considered objective evidence of excessive sleepiness. Additionally, any nap opportunity during which REM sleep onset was noted within 15 minutes is marked as a "sleep-onset REM period (SOREMP)." In the appropriate context, more than 1 SOREMP between the preceding PSG and the MSLT may support a diagnosis of narcolepsy. Results must be interpreted cautiously as comorbid sleep disorders, medications, or recreational drug use can affect REM sleep onset. References External links Mary Carskadon's page on the MSLT Diagnostic neurology Sleep