Neurology

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Multiple Sleep Latency Test - MSLT
Neurodiagnostic/Sleep Lab, 319-398-6097

What is an MSLT?

It is a test that consists of a series of five, twenty-minute nap periods scheduled two hours apart. The patient is given five opportunities to sleep during their customary awake period. Measurements of the interval from the start of the nap period to the first sign of sleep are measured for each nap.       

Why should I have an MSLT?

Here are several reasons for having an MSLT:

• To test for Narcolepsy
• To distinguish physical tiredness from true excessive daytime sleepiness
• To document sleep/breathing disorder 
  treatment is effective

Procedure:

The patient routinely has a formal sleep study the night before the day of the MSLT. The patient is sent to the Laboratory department for a urine toxicology screen prior to the start of an MSLT. This is done to rule out the possibility of the patient knowingly or unknowingly ingesting medications that have an adverse effect on sleep. 

Once the patient is back in the department, the recording preparation begins. Scalp electrodes are applied to the head with special glue and used to record brain waves. Electrodes are taped by the eyes to record eye movements. Muscle tone is recorded from the chin and the heartbeat is also monitored.

After hook up, the patient is instructed to relax quietly in a bed or in a recliner. Patients are instructed to perform several simple tasks to document and check that all equipment is functioning properly. Once all the equipment is calibrated and checked the nap period will begin with a verbal “Good Night”. 

The technologist determines the length of each nap based on the whether the patient sleeps or not. Nap periods can be as short as 16 minutes if sleep is achieved in the first minute of the nap period or as long as 35 minutes if sleep is achieved in minute 20 of the nap period. 

If no sleep is achieved the nap period will be 20 minutes long. Data from all 5 nap periods are used to determine the severity of the patient’s daytime sleepiness. After the final nap period the electrodes and glue are removed from the patient’s hair. Any remaining glue residue will wash out after several shampoos. 

There are no side effects from the test. A neurologist will review your data and a formal report will be sent to the referring physician as soon as it is available. Your physician will go over those results with you and determine a course of follow-up care.

Preparation:

ALL PATIENTS: Please arrive with clean dry hair and scalp. Refrain from use of hair products such as hairspray, gel, oil, or mousse. Take medications as you normally would unless instructed differently by your physician.

PATIENTS NOT UNDERGOING A FORMAL SLEEP STUDY THE NIGHT BEFORE are asked keep a sleep diary logging the amount and times they have slept over the past week.

Outpatient Registration:

If you are not having a sleep study done the night before please arrive 15 minutes prior to your scheduled procedure. Park in the Mercy Medical Center Parking Ramp, located at the corner of 8^th Street and 8^th Avenue SE. (The South Entrance into the hospital from the parking ramp is the closest to Registration.)  You must register PRIOR to your procedure.  Upon entering the hospital, proceed to Ground (G) level and follow the signs to “Registration.”  After registering, follow the signs to “Neurodiagnostic/Sleep Lab”, located on 3rd floor. If you are having a sleep study the night before you will already be registered for the MSLT.

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