There are a few methods for diagnosing an individual for narcolepsy, the disease which affects one in 2000 people annually. While a self-evaluation using Epworth Sleepiness Scale can give a person some general idea, one still needs to consult a medical professional for formal diagnosis in order to receive a treatment for narcolepsy disorder. The diagnostic process usually begins with a sleep study where a person has to stay overnight in a sleep lab.
Typically, the first overnight test for narcolepsy is a polysomnogram. The purpose of the polysomnogram is to record the individual’s brain waves, breathing, and muscle tone which helps to evaluate the quality of sleep the person is receiving as well as the amount of sleep that serves to detect possible evidence of another sleep disorder such as sleep apnea or periodic limb movement; an example of the latter being a condition known as restless leg syndrome where an individual’s leg jerks during the night uncontrollably while they are sleeping.
After the polysomnogram is taken, the individual will arrive next day for continued observation. The next step in the process is Multiple Sleep Lating Test, or MSLT. You will want to make sure that you get sufficient sleep prior to taking this test. Also, your doctor will want you to temporarily discontinue any medications, otherwise they could affect your sleep and the results of the test.
The MSLT consists of the five twenty minute naps every two hours throughout the following day after the overnight stay. This test is performed after the polysomnogram so that the doctor can better make a determination as to whether or not the previous nights sleep is affecting the patient’s naps during the day.
Preparing for the sleep tests
There are a wide variety of factors that can cause either or both tests to become disrupted which is why it is important to work with your doctor closely before having any kind of a test performed prior to the actual testing. The most likely recommendation by the doctor is to discontinue any medication that directly affects the brain for anywhere from one to three weeks prior to testing. Examples of these types of medications are painkillers, the drugs that are taken to help increase alertness, to improve concentration in people with ADHD, or certain medications used to treat depression (e.g. SSRI type antidepressants).
It is also worth noting that since the person with the sleep disorder will need to have a more regular sleep schedule so as to ensure better accuracy of the test that the doctor may suggest the individual keep a sleep diary for at least a week or two. The main purpose of the sleep diary is to rule out the possibility of insufficient sleep as the cause of sleepiness.
Something else the doctor may recommend for the sleep patient is that they wear a device which resembles a wristwatch in the weeks leading up to the test to help measure the daily activities of the sleep deprived person. This type of test is known as wrist-based actigraphy and serves to record the body’s movements as well as estimate the amount of sleep that the person is receiving on a nightly basis. Of course if the sleeper cannot get out of the habit of waking up after eight o’ clock in the morning, then the doctor may feel the need to rearrange the sleep test to better suit the schedule of the person being tested.
Understanding the results of the tests
One of the main criteria for diagnosis of narcolepsy (with cataplexy) is that most narcolepsy patients enter REM (rapid eye movement) sleep phase within fifteen minutes since falling asleep. Other features that the polysomnogram reveals are an individual dozing within five minutes from going to bed and/or having light non-REM sleep that is greater than normal.
During the MSLT, a person falling asleep during the first eight minutes of the nap and entering into REM sleep in at least two of the five naps will lead to a diagnosis of narcolepsy with cataplexy. Those patients who are diagnosed with narcolepsy without cataplexy will more than likely take longer to doze off and rarely enter into REM sleep.
If a person does turn out to have narcolepsy, it will be obvious that they are prone to doze off more quickly whether they have a good night’s sleep or not as well as a more impaired regulation of their REM sleep.
To conclude, polysomnogram and MSLT are the main two tests used by medical professionals to diagnose narcolepsy. A self-evaluation is an individual test which is basically in questionnaire form and only serves to give the individual a general idea as to whether they have narcolepsy or any other sleep disorder. The only other test not mentioned in this article is where the doctor checks the person’s level of hypocretin-1 in their spinal fluid. Low level of hypocretin-1 could result in a loss of positive emotions leading to depression, it can also make an individual feel very tired and result in inadequate amount of sleep.