Narcolepsy is one of the conditions that cause hypersomnia or excessive uncontrollable tendency to sleep. There are many other conditions that may cause hypersomnia, but narcolepsy is distinctly different.
What exactly is the problem in narcolepsy?
In an area of brain called hypothalamus, there are cells that secrete a hormone called hypocretin. These cells get activated during daytime, and secrete this hormone. Hypocretin influences many other areas of brain, which are involved to keep us awake This is achieved by secretion of many activating or alerting chemicals like nor-epinephrine, dopamine, serotonin, and histamine.
In narcolepsy, brain starts losing hypocretin-secreting cells resulting in its deficiency, which subsequently leads to deficiency of activating chemicals. Low levels of alerting chemicals cause decreased alertness and hypersomnia. Deficiency of hypocretin also takes the pressure off REM sleep and it starts appearing at abnormal timings, which causes cataplexy.
What conditions may cause hypersomnia?
A: Sleep deprivation: A normal person requires at least 7-8 hours of sleep a day. Chronic sleep deprivation is a very common problem in all societies. Even sleeping an hour less for a few days may lead to a constant urge to sleep.
B: Drugs: Many prescription drugs may cause sedation and constant urge to sleep, e.g., many psychiatric drugs.
C: Underlying illnesses: Many medical and psychiatric illnesses.
D: Obstructive sleep apnea
E: Hypersomnia of unknown cause (Idiopathic Hypersomnia)
F: Klein-Levin Syndrome
G: Alcohol abuse
H: Head trauma
I: Narcolepsy
What are the symptoms of narcolepsy?
There are four main symptoms of narcolepsy:
- Hypersomnia
- Cataplexy
- Sleep paralysis
- Sleep related hallucinations
Not every patient has all four symptoms, and all symptoms may not appear all the time. Following is more details about these symptoms:
Hypersomnia: It occurs in spite of appropriate hour of sleeping.
Cataplexy: This symptom differentiates Narcolepsy Type 1 from Type 2; Type 1 has cataplexy and the Type 2 does not. It is sudden loss of muscle tone when the person is having strong positive emotions, such as surprise or laughter. If standing, the person may fall down, without losing consciousness. It may also affect a part of the body like jaw, neck, arms or legs. Cataplexy is so unique symptom that its presence alone may make the diagnosis of narcolepsy.
Sleep paralysis: It is a fascinating but scary symptom, which typically happens upon waking up in morning hours. Person comes out of sleep and notices complete paralysis of the body, except eyelids. The episode lasts only for a few seconds but may cause extreme fear and anxiety. Many “normal” people experience sleep paralysis without an indication of a sleep disorder.
Sleep related hallucination: This is another scary symptom. Vivid hallucinations lasting for a few seconds may happen while going into sleep (hypnogogic hallucinations) or upon waking up (hypnopompic hallucinations).
How is narcolepsy diagnosed?
If someone has hypersomnia or an uncontrollable urge to sleep with no obvious explanation, it requires investigations. After history taking, examination, and routine labs, if no explanation is found, a diagnosis of narcolepsy is suspected. Because of similarities of symptoms, some patients may require an EEG to rule out seizure disorder.
With the right history, and well-documented episodes of cataplexy, the diagnosis of narcolepsy may be easy to make. But most cases are not straightforward and require further investigations. There are two ways to make a diagnosis of narcolepsy: a sleep study or a lab test.
Sleep study to diagnose narcolepsy: This is the traditional way of making this diagnosis An overnight sleep study is performed to document full-night’s sleep, and to rule any other sleep conditions that may cause hypersomnia, such as obstructive sleep apnea. On the morning after the sleep study, the patient is asked to stay awake and not take any caffeine, a stimulant or a sedative. Another sleep test called Multiple Sleep Latency Test (MSLT) is performed in morning hours. Patient is brought to the sleep lab and asked to try to take series of naps, about one every 90 minutes. For a normal person, it is not easy to go back to sleep after sleeping overnight. Generally speaking, it is difficult to go to sleep within 15 minutes of trying. Patients with hypersomnia may go to sleep much quicker, in a few minutes, or at least less than 8 minutes.
Other than determining onset of sleep in minutes, the test also determines the onset of REM sleep. REM is the last part of every sleep cycle, preceded at least by some non-REM sleep. Patients with narcolepsy go into REM sleep quicker than normal people, in less than 15 minutes of sleep, which is called sleep-onset REM, or SOREM.
If a patient’s sleep onset is less than 8 minutes on more than one naps; hypersomnia is confirmed. If the patient also has two or more SOREM episodes, the diagnosis of narcolepsy is established. The rule of 8 minutes works better to make a diagnosis of narcolepsy, and not as well for other conditions causing hypersomnia.
Lab test to make a diagnosis of narcolepsy: Patients with narcolepsy have low level of a hormone called hypocretin in their spinal fluid. Spinal fluid is obtained by performing a lumbar puncture and sent for hypocretin level. In a way, logistically speaking, it is an easier way of making the diagnosis.
What are different causes of narcolepsy?
A: Genetics: There likely is a genetic reason or an abnormal gene causing Narcolepsy. There are some indications but the exact nature of the abnormality is not well defined.
B: Autoimmunity: According to this theory, an autoimmune process selectively destroys hypocretin-secreting cells in the brain. This may be the reason that in some cases narcolepsy may occur after a viral or a bacterial infection.
What are risks of untreated narcolepsy?
Untreated narcolepsy, due to its tendency to put a patient to sleep in odd situations, is a risk for physical injury, especially while driving or working with heavy machinery. Similarly, cataplexy may be a risk for physical injury due to the possibility of falling, or losing muscle tone at a wrong place and time.
How is narcolepsy treated?
No specific treatment is available to treat narcolepsy, which means that there is no treatment available at this time to replace the lost hypocretin secreting cells, or to replace the hypocretin itself. Instead, its symptoms are treatable. Following are the commonly used drugs to treat symptoms of narcolepsy:
For Hypersomnia:
First choice
Modafanil (Provigil)
Pitolisant (Wakix)
Sodium oxybate (Xyrem)
Solriamfetol (Sunosi)
Second choice
Armodafanil (Nuvigil)
Dextroamphetamine
Methylphenidate
Third choice
Amphetamine
Lisdexamfetamine
For Cataplexy:
SSRIs: e.g., fluoxetine, sertraline, paroxetine, citaloprim
SNRIs: e.g., venlafaxine
Tricyclics: e.g., clomipramine, imipramine, protriptyline
What measures other than meds can help?
- Regular or structured sleep schedule according to the need (feeling of slept appropriate amount), which may vary for different individuals.
- Take regular one or two (or more) naps during the day at times of maximum drowsiness.
- Avoid sleep deprivation.
- Avoid screen time or anything stimulatory a few hours before sleep time.
- Avoid caffeine at least 5-6 hours before sleep.
- Have dinner earlier than closer to the sleep time.
- Avoid alcohol altogether.
- Counseling for the patient and the family, e.g., spouse.
- Avoid certain professions, such as any profession requiring driving.
Where can I get more information about narcolepsy?
American Academy of Neurology
American Academy of Sleep Medicine
Leave a Reply
Your email is safe with us.
You must be logged in to post a comment.