What To Expect MSLT
What is a Multiple Sleep Latency Test (MSLT) and What Should You Expect?
The Multiple Sleep Latency Test (MSLT) is a standard tool used to measure the degree of daytime sleepiness and to assist in the diagnosis of certain sleep disorders, such as narcolepsy and idiopathic hypersomnia. It measures how quickly you fall asleep when resting during the day. This test is typically performed the day immediately following an overnight sleep study (polysomnogram).
Before the MSLT
In an effort to gain the most accurate results, please see the instructions below for the weeks leading up to your MSLT:
- Sleep Log: A daily sleep log should be maintained for at least two weeks before the test, recording the time you go to bed, wake up, and any naps you take to help ensure a consistent sleep-wake schedule and getting adequate sleep. Bring this completed log with you to your follow up appointment.
- Medications: Consult with your physician regarding any medications you are taking. Certain medications such as certain antidepressants and stimulants can affect sleep and may need to be temporarily weaned off prior to the test. Do not stop taking any prescribed medication without your doctor's approval.
- Stimulants: Ideally, avoid caffeine, alcohol, and nicotine products for at least one week prior to the test. This includes coffee, tea, soda, chocolate, and any over-the-counter or prescribed stimulants.
- What to Bring:
- Meals for the next day (breakfast and lunch), snacks, non-caffeinated drinks
- Comfortable sleep items (pajamas, pillow, blanket)
- Entertainment for downtime (laptop/computer, phone, books, headphones, chargers)
- Toiletries and a change of clothes Any regular medications (as instructed)
- Reminders: Avoid caffeine the morning of the MSLT and arrive with clean, product-free hair, and remove nail polish/acrylic nails.
Complete Overnight Study: The MSLT must be preceded by an overnight polysomnogram (PSG) to rule out other sleep disorders and ensure you have had adequate sleep.
Day of the MSLT
- Arrival and Preparation:
- The MSLT will start the morning after your overnight PSG at the sleep lab located on the first floor of VHC (1 North) at 1635 N. George Mason Dr. Arlington, VA 22205
- The PSG electrodes will remain in place, and a sleep technologist will monitor you throughout the day.
- You can elect to sleep with a CPAP during your naps if you have previously been prescribed one.
- The MSLT Procedure:
- The test consists of four or five scheduled "nap opportunities," each lasting about 20 minutes.
- The nap opportunities are scheduled approximately two hours apart, beginning about 1.5 to 3 hours after you wake up from the PSG.
- A sample schedule is as follows, but exact times may vary:
- Nap 1: 8 AM
- Nap 2: 10 AM
- Nap 3: 12 PM
- Nap 4: 2 PM
- (Nap 5: 4 PM)
- During Nap Opportunities:
- You will be instructed to lie quietly in bed in a dark, quiet room and try to fall asleep.
- The technologist will record your brain waves, eye movements, and muscle activity.
- If you fall asleep, the technologist will wake you up 15 minutes after sleep onset.
- If you do not fall asleep within 20 minutes, the nap opportunity will end.
- Please do not distract yourself with electronic devices during the nap opportunity - a delay in napping can result in a delay in diagnosis and a delay in your care.
Between Nap Opportunities (Inter-Nap Periods)
It is crucial to remain fully awake between the scheduled naps to avoid affecting the results.
- You must stay out of bed.
- You may read, watch TV, use your phone, or work on a laptop.
- You must not ingest any stimulants, including caffeine, nicotine, or alcohol.
- You should avoid strenuous physical activity.
- Do not nap, even for a few minutes. If you accidentally fall asleep, inform the technologist immediately.
Scheduling and Contact Information
Please confirm your scheduled date for the MSLT and PSG by calling PMA Health Sleep Lab at 703-236-7171.
Please bring all necessary forms and insurance information to your appointment.