How Doctors Diagnose Narcolepsy — and Why the Disorder Can Be So Difficult to Identify
Narcolepsy is a chronic neurological disorder in which sleep and wake intrude onto one another, leading to sleepiness in the daytime and disrupted sleep at night, according to the National Heart, Lung, and Blood Institute. Feeling extremely fatigued and constantly falling asleep (sometimes uncontrollably) during the day are symptoms you may experience with this sleep disorder, per the National Institute of Neurological Disorders and Stroke (NINDS).
Narcolepsy can have very debilitating side effects, but the important point to know is that there are medications and other lifestyle modifications that individuals can follow to help manage the condition and lead full lives, notes Stanford Medicine’s Center for Narcolepsy.
For any of those narcolepsy treatments to help, however, the first step is getting an accurate diagnosis. And while certain narcolepsy symptoms — such as sudden sleep “attacks” and cataplexy (sudden loss of muscle tone and control) — are fairly unique, other narcolepsy symptoms and the ones that tend to show up earlier on are ones that could be missed or overlooked as another problem, according to the National Sleep Foundation.
The primary symptom of narcolepsy is excessive daytime sleepiness. That’s one major reason many people who have narcolepsy may not realize that they have a problem or get a proper diagnosis for years. A number of physical or psychological conditions, such as obesity or depression, can also cause excessive sleepiness during the day, according to the American Academy of Sleep Medicine (AASM).
“Narcolepsy is often misdiagnosed as not getting enough sleep,” says Eric Olson, MD, associate professor of medicine, sleep medicine specialist at the Mayo Clinic, and board member of the AAASM.
In many cases, people who are sleepy don’t seek help, sometimes for years, because they assume being sleepy isn’t a sign that they may have a disease. “Those with mild symptoms don’t go to the doctor,” says Emmanuel Mignot, MD, a professor of psychiatry and behavioral sciences at Stanford University in California and the director of the Stanford Center for Sleep Sciences and Medicine.
And when they do see a doctor for a checkup or an illness, they may not even mention their chronic daytime sleepiness. “Patients might not bring it up with their doctor,” says Dr. Olson.
But daytime sleepiness is a problem you should talk to your doctor about for a proper diagnosis, Olson says, along with any other symptoms that could be a narcolepsy red flag, including:
Cataplexy — a sudden loss of muscle tone and control typically triggered by strong emotions like joy, surprise, excitement, terror, or anger
Hallucinations
Sleep paralysis, which can sometimes occur at the same time as hallucinations
If you are experiencing symptoms that might be narcolepsy, the first step is telling your primary care doctor. To diagnose narcolepsy, he or she will likely ask any or all of the following questions to understand more about what you are experiencing and whether or not you should see a sleep medicine specialist:
What does your typical sleep schedule look like?
Do you have trouble falling asleep or staying asleep?
Do you feel fatigued or experience sleepiness during the day?
Have you experienced other narcolepsy symptoms, such as cataplexy, hallucinations, or sleep paralysis?
What medication are you taking? Some medications, such as pain relievers containing caffeine, antidepressants, or antihistamines, can disrupt your sleep and cause daytime drowsiness.
Do you use drugs or alcohol? How much? How often?
Have you recently suffered an infection (such as the flu) or brain injury? Do you have an autoimmune disorder? These are factors that could potentially lead to narcolepsy.
Do you have any relatives who have narcolepsy, or who had symptoms that could have possibly been narcolepsy but were never diagnosed? (While narcolepsy isn’t hereditary, the genetic disposition to develop the sleep disorder may be inherited, says Dr. Mignot.)
It’s important to know that your doctor may not ask about daytime fatigue or your sleep during a regular checkup, but not getting restful, restorative sleep on a regular basis is a potential warning sign for narcolepsy. You should bring up persistent sleep issues with your doctor.
To help determine if your sleep complaints might be narcolepsy, your doctor may ask you to keep a sleep diary for a few weeks that tracks how many hours you sleep each night, when you sleep, how quickly you fall asleep at night, whether you experience sleepiness during the day, and whether (and how much) you nap during the day.
In most cases, primary care doctors will recommend that you see a sleep medicine specialist to further discuss your symptoms and make a narcolepsy diagnosis. But some primary care doctors do have sleep medicine expertise and may be able to make a diagnosis themselves.
If the initial medical exam and at-home monitoring with self-reported sleep logs indicate potential narcolepsy, doctors then rely on two sleep tests that are performed at a sleep center to look for the cause of the symptoms and determine whether you have narcolepsy or another sleep disorder, explains Shelley Hershner, MD, an assistant professor of neurology and the director of the Collegiate Sleep Clinic at the University of Michigan in Ann Arbor.
Polysomnogram For a polysomnogram the patient stays overnight at the sleep center while technicians record data about their brain activity, heart rate, blood pressure, and eye movements. The test can help determine whether your sleep cycle is normal — going into nonrapid eye movement (NREM) and then progressing into REM after an hour or more — or if it indicates narcolepsy (you fall asleep quickly and go right into REM sleep, and then have trouble staying asleep throughout the night).
Multiple Sleep Latency Test (MSLT) This full-day sleep test is done on the day after the polysomnogram, and it’s designed to measure how sleepy you are during daytime. It determines how quickly you fall asleep during the day after a full night’s sleep (the previous night in the lab), and it also measures how quickly a person falls asleep and enters REM sleep during a daytime nap.
The sleep test takes place over the course of a day. You will be asked to take five scheduled naps with two-hour breaks in between. During each of the scheduled naps you lie in a dark, quiet, and comfortable room and try to sleep. Then, technicians will measure how long it takes you to fall asleep. If you fall asleep, they wake you up after 15 minutes; if you do not fall asleep after 20 minutes, the technician will stop that nap session, per the AASM.
Before the sleep test, your doctor will likely order blood and urine tests to screen for substances that can cause false positives.
In rare cases your doctor might additionally order a test to measure the levels of the brain hormone hypocretin-1 in the fluid that surrounds the brain and spinal cord, known as a spinal tap or lumbar puncture, according to NINDS. Unless you have another serious medical condition that affects hypocretin levels, low levels are nearly always an indicator of type 1 narcolepsy, though narcolepsy cannot be diagnosed by this test alone.
While there have been vast improvements in understanding and diagnosing narcolepsy, there are still challenges that can delay diagnosis — including the fact that the symptoms of narcolepsy often overlap with other disorders, including depression, anxiety disorders, and other psychiatric illnesses. In some cases individuals with the symptoms may delay seeking help because they don’t understand the symptoms they’re experiencing — hallucinations or cataplexy, for instance — or may not be sure what to tell their doctor.
Narcolepsy symptoms can also be mistaken for those of a seizure disorder or another sleep disorder when someone experiences a cataplexy attack or chronically falls asleep during the day. And in some cases, narcolepsy symptoms are neglected because of a wrongful assumption that an individual is just “lazy.”
If left undiagnosed or untreated, narcolepsy can interfere with one’s psychological, social, and cognitive function. It can also have a negative impact on school performance in children, on work, and on social relationships and activities. Unfortunately it can also lead to psychological problems, including depression, Olson notes. “Some people wonder, ‘Why am I different?’ and feel like they’re failing in school, can’t keep a job, and are failing in life.”
Someone with narcolepsy may avoid some of the joys in life that can trigger symptoms, such as laughing, activities that cause excitement, or even sex if they’re prone to falling asleep during intercourse, Olson says. “It can be life-restricting.”
For all these reasons, don’t ignore symptoms, and get an accurate diagnosis.
