How to Prepare a Patient for an MSLT
Instruct the patient to wear a wrist actigraphy device for 7–14 days before the test to objectively document their sleep-wake patterns and ensure they are getting adequate sleep each night. 1, 2
Pre-Test Sleep Monitoring
- Actigraphy is essential because it provides objective data that sleep logs cannot match—patients tend to overestimate their sleep time by approximately 1.5 hours per night on self-reported logs, and actigraphy is the only method that shows a significant relationship between nighttime sleep duration and MSLT results. 1
- The patient should maintain a concurrent sleep diary alongside actigraphy to document any unusual activities or circumstances. 1
- The goal is to document adequate total sleep time (typically at least 6 hours for adults on the overnight polysomnography, and 7 hours for children) to distinguish true organic hypersomnolence from insufficient sleep syndrome. 2, 3
Medication Management
All stimulants and sedating medications must be discontinued before testing. 4, 5
- Stop stimulants: amphetamines, methylphenidate, modafinil, and similar agents that can mask sleepiness. 4, 5
- Stop sedating medications: benzodiazepines, hypnotics, antihistamines, and other sedating substances. 4, 5
- Failure to discontinue these medications will invalidate the MSLT interpretation. 5
Sleep Requirements Leading Up to the Test
- Ensure the patient gets adequate sleep for at least 7–14 days before testing—chronic sleep deprivation is the most common cause of false-positive MSLT results. 1, 2, 5
- The patient should maintain regular sleep-wake schedules during this period. 1
- On the night immediately before the MSLT, the patient must undergo overnight polysomnography to rule out other sleep disorders (sleep apnea, periodic limb movements) and to document adequate sleep time. 2, 5
- The patient should not be discharged between the PSG and MSLT—the MSLT must be performed the morning immediately following the overnight sleep study. 2
What to Expect on Test Day
- The MSLT consists of 4–5 nap opportunities spaced 2 hours apart throughout the day. 5, 6
- Each nap trial allows up to 20 minutes for the patient to fall asleep in a dark, quiet room while lying in bed. 5
- The test measures how quickly the patient falls asleep and whether REM sleep occurs during these naps. 5, 6
Common Pitfalls to Avoid
- Inadequate prior sleep is the leading cause of misdiagnosis—emphasize to the patient that getting sufficient sleep in the weeks before testing is not optional. 1, 2, 5
- Patients may minimize their sleep disruption on sleep logs when job status or disability determinations are at stake, which is why objective actigraphy is superior. 1
- Screen for and address comorbid sleep disorders before interpreting the MSLT, as conditions like sleep apnea can alter test results. 5