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Unlocking a Narcolepsy Diagnosis: What to Expect During Sleep Testing
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Navigating a potential narcolepsy diagnosis can be daunting, but understanding the testing process – including polysomnography (PSG) and the multiple sleep latency test (MSLT) – is a crucial first step. While no two experiences with narcolepsy are exactly alike, these two tests are considered essential for confirming a diagnosis.
A sleep medicine specialist and narcolepsy expert, Brynn K. Dredla, M.D., of Mayo Clinic in Jacksonville, Florida, explains that comprehensive sleep center testing is key to understanding this complex condition.
Preparing for Narcolepsy Testing: The Sleep Diary and Actigraphy
If your healthcare provider suspects you may have narcolepsy, the initial step typically involves meticulous record-keeping. According to Dr. Dredla, patients are usually asked to maintain a detailed sleep diary for two weeks leading up to the PSG and MSLT. This diary should include:
- Wake-up and bedtime.
- Total sleep duration.
- any nighttime sleep disturbances.
- Instances of daytime sleepiness.
- Self-reported levels of alertness.
- How rested you feel.
Along with a sleep diary, you might potentially be asked to wear an actigraph – a wristwatch-like device that monitors sleep duration, light exposure, activity levels, and rest periods.
This detailed preparation isn’t merely procedural. “It’s important to make sure you aren’t sleep deprived, which can result in false positive results,” Dr. Dredla explains. Generally, aiming for at least six hours of sleep per night for two weeks prior to testing is recommended. Moreover, aligning the tests with your natural sleep patterns is vital.
“Let’s say I am a night owl and I have a circadian rhythm issue,” Dr. Dredla illustrates. “I would want to do my testing when I’d be the most awake and when I’d be the most sleepy. That might be 1 a.m.to 9 a.m., and that’s very different from someone who is a morning person.”
Polysomnography (PSG): A Comprehensive Overnight Sleep Study
The PSG is an overnight test conducted in a sleep center. During the PSG, sensors are attached to your scalp, face, chest, and legs to monitor various physiological parameters, including:
- Brain waves (EEG)
- Eye movements (EOG)
- Muscle activity (EMG)
- Heart rate
- Breathing patterns
- Oxygen levels
“We’re looking for any sleep disorders that might be contributing to your symptoms,” Dr. Dredla explains. “we’re also looking at the architecture of your sleep – how you move through the different stages of sleep.”
Multiple Sleep Latency Test (MSLT): Assessing Daytime Sleepiness
The MSLT is typically performed the day after the PSG. It measures your propensity to fall asleep during the day. You’ll be asked to take four to five 20-minute naps, spaced two hours apart.
“during the MSLT, you’ll be in a darkened room, and we’ll monitor your brain activity to see how quickly you fall asleep,” Dr. Dredla says. “The average time it takes to fall asleep is measured in minutes.”
after each nap, you’ll be awakened, and the cycle is repeated five times, with two-hour intervals between each possibility to sleep.
“If you fell asleep on average across those five nap opportunities, within or equal to eight minutes, that’s considered excessively sleepy, which is one criterium for narcolepsy,” Dr. Dredla states. “The second criterium is if you go into REM sleep at least twice.If yes, then that is how you would confirm a diagnosis of narcolepsy.” Reaching REM sleep within 15 minutes during the PSG also confirms a diagnosis.
It’s important to note that the MSLT isn’t foolproof and may require repetition due to the possibility of false positives and false negatives. “You may have very classic clinical symptoms, and if your testing wasn’t consistent or we didn’t see you go into REM sleep, we sometimes repeat it,” Dr. Dredla notes.
Alternative testing and Ongoing Monitoring
While a sleep center is ideal, access and insurance coverage can be barriers.
