What Is An Polysomnogram (PSG) with MSLT?

A polysomnogram (PSG) is a sleep study that helps determine whether or not you have a sleep disorder. While you sleep, sleep patterns and behaviors such as brain waves, heart rate and breathing, eye and leg movements, and the oxygen level in your blood are recorded. A PSG can be done at night or during the day and a trained sleep technologist supervises the sleep study.

The multiple sleep latency test (MSLT) determines excessive daytime sleepiness by measuring how quickly you fall asleep in a quiet situations during the day, and how quickly and how often you enter REM sleep. The MSLT is sometimes referred to as the daytime nap study and is used to diagnose narcolepsy or idiopathic hypersomnia. It is always a follow-up test to the overnight PSG which is used to rule out other sleep disorders such as sleep apnea, restless leg syndrome and parasomnias.

When you arrive for your sleep study, a Registered Polysomnographic Technologist (RPSGT) or Registered Respiratory Therapist (RRT) will be at the site to greet you and show you to your room. After you make yourself comfortable, your technologist will take a brief history, explain the study process, and answer any questions you may have prior to applying the sensors.

What To Expect

Getting Ready

First, the technologist will use stickers to affix leads on your legs and chest. You will also have two belts placed around your chest and abdomen that monitor your body’s efforts to breathe.

Next, your head will be marked and measured with a paper ruler and a grease pencil. This is done because each electrode on your head needs to be in a precise location. Once this is complete, a skin prep jelly will be applied to clean the scalp for the electrodes.

Electrodes are then placed on the surface of your scalp with a small amount of paste. The prep, paste, and tape are hypoallergenic.

You'll also have a nasal cannula (similar to an oxygen cannula) to monitor your breathing. You will not receive oxygen during your PSG.

This process is completely painless and generally takes about 40 minutes to make sure everything is placed correctly.

Testing

Once you’re fitted with the sensors, you can relax in your room, catch up on phone calls, enjoy Cable TV, Wi-Fi, or read until "Lights Out" at 11pm. Yes, you may eat, drink, and use the bathroom throughout the night! We want you to feel comfortable and relax as you would at home prior to going to sleep. You may bring your own food/snacks. Should you need to get up at all during the night, simply let your technologist know.

Your technologist will monitor your sleep throughout the study and will be available to answer questions and ensure you’re comfortable.

In the morning, the technologist will remove some of the sensors used the night before and will explain the multiple sleep latency test (MSLT), during which you will have 5 half hour naps with the first one beginning at about 8:00am. In between naps, you can relax, catch up on phone calls or read. Please be certain to bring snacks or lunch.

All Done, Now What?

When the study is done in the morning, the technologist will waken you and remove the wires and sensors. Any remaining paste or marks can be easily washed out using warm water and shampoo.

At your follow-up appointment, you will receive your sleep study results and discuss them with your provider.