If a doctor suspects narcolepsy, he or she will likely recommend sleep studies. These tests are essential to provide clear evidence of sleepiness, to examine the pattern of rapid-eye-movement (REM) sleep, and to determine whether other disorders might be contributing to a patient’s symptoms. Show Types of sleep tests A polysomnogram is a recording of brain waves, eye movements, muscle tone, and breathing across a night of sleep. In people with narcolepsy, the polysomnogram is done to evaluate the amount and quality of nighttime sleep and to look for any evidence of an additional sleep disorder (for example, sleep apnea or periodic limb movements in sleep). The Multiple Sleep Latency Test is often the most important test for diagnosing narcolepsy. It is a series of five scheduled naps spread across the day. Every two hours, the patient is given an opportunity to sleep for 20 minutes or more. The MSLT is done the day after the polysomnogram so a doctor can determine whether the prior night’s sleep could be affecting the daytime naps. Diagnostic Tests (1:13) Dr. Scammell describes how a polysomnogram and a multiple sleep latency test (MSLT) are used in diagnosing narcolepsy. Preparing for sleep tests A doctor will usually recommend that a patient stop, one to three weeks prior to the tests, any medications that can affect the brain. This is especially important for medications used to treat depression, drugs that increase alertness, and drugs that have the potential for abuse or addiction, such as amphetamines or cocaine. Keeping a Sleep Diary (0:40) Dr. Maski explains the value of using a sleep diary. It is important to obtain enough sleep before the tests. A doctor may request that a patient keep a sleep diary for one to two weeks before the tests to be certain that insufficient sleep is not a contributing factor. Download the printable Sleep Diary (PDF) to track your sleeping patterns. During this period the doctor might also want to measure a patient's activity using a technique known as wrist-based actigraphy. For this, the patient is asked to wear a device resembling a wristwatch that records body movements to estimate amounts of sleep. If someone has a tendency to routinely sleep later than 8 a.m., the doctor may recommend changes to the sleep schedule or timing of the sleep tests. Understanding test results The polysomnogram may also show that an individual dozes off in less than five minutes or has greater-than-normal amounts of light non-REM sleep, but these phenomena are not decisive for a diagnosis. This test is also helpful in identifying any additional sleep disorders (for example, sleep apnea or periodic limb movements in sleep) that could contribute to poor quality sleep. If someone has narcolepsy, the MSLT usually reveals that the person falls asleep rapidly (in less than eight minutes on average across the naps) and enters REM sleep during two or more naps. This pattern on the MSLT is considered highly suggestive of narcolepsy. In contrast, most people without narcolepsy take much longer to fall asleep during naps, and if they do fall asleep, they rarely enter REM sleep. The MSLT results can highlight two major indicators of narcolepsy:
Sometimes the results of the MSLT are unclear, and a doctor may recommend repeating the test if he or she thinks narcolepsy is likely. Other tests Although most people who have narcolepsy carry a genetic marker (HLA-DQB1*06:02) associated with the disorder, this gene is only a predisposing factor to developing narcolepsy. Testing for it will not confirm a diagnosis of the disorder. In fact, this gene is moderately common in the general population, so it provides only modest diagnostic evidence. Still, some doctors find the test helpful when symptoms are atypical. References
Which statement about narcolepsy is true?Which statement about narcolepsy is true? It is chronic and lifelong. The sleep disorder that involves an episode of walking or performing other actions during Stage 3 or Stage 4 NREM sleep is called _____.
Which describes narcolepsy quizlet?Which of the following best describes narcolepsy? A sleep disorder that involves excessive, uncontrollable daytime sleepiness.
What is the main cause of narcolepsy?What causes narcolepsy. Narcolepsy is often caused by a lack of the brain chemical hypocretin (also known as orexin), which regulates wakefulness. The lack of hypocretin is thought to be caused by the immune system mistakenly attacking the cells that produce it or the receptors that allow it to work.
Can you have narcolepsy and insomnia?Fragmented sleep and insomnia.
While individuals with narcolepsy are very sleepy during the day, they usually also experience difficulties staying asleep at night. Sleep may be disrupted by insomnia, vivid dreaming, sleep apnea, acting out while dreaming, and periodic leg movements.
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