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Even if you get enough sleep, if you suddenly feel an overwhelming urge to sleep during the day, you might worry if you have some kind of illness.
This article explains the causes and specific symptoms of narcolepsy, a type of hypersomnia, as well as the characteristics of people who are prone to it and how to deal with it, for those who are wondering whether they should go to the hospital and want to know about coping strategies.
What is Narcolepsy?
According to the Ministry of Health, Labour and Welfare's "Narcolepsy | e-Health Net (Ministry of Health, Labour and Welfare)," "Narcolepsy is a type of hypersomnia that has been known for a long time, and it is a disease in which a sudden, strong urge to sleep appears during the day, causing one to fall asleep."
The sleepiness of narcolepsy is intense and is called a sleep attack, and one may fall asleep even when it is absolutely necessary to stay awake. Because one falls asleep before realizing that sleepiness has struck, the person themselves may not even realize that they have dozed off.
It also states, "Characteristic symptoms of narcolepsy include cataplexy (emotional loss of muscle tone) where the whole body or a part of the body loses strength when surprised or laughing heartily, hallucinatory experiences that appear at the onset of sleep (hypnagogic hallucinations), and sleep paralysis (kanashibari) that appears at the onset of sleep."
Causes of Narcolepsy
In recent years, it has been discovered that narcolepsy is caused by the dysfunction of hypocretin-producing neurons (hypocretin neurons or orexin neurons) in the brain, which are necessary for maintaining a state of wakefulness.
However, the exact cause has yet to be identified, and it is said that winter infections such as influenza may affect autoimmune processes, potentially leading to narcolepsy several months later, and head injuries may also be a trigger.
Furthermore, in the case of identical twins, if one twin has narcolepsy, the other may also develop it, suggesting a genetic factor.
Four Major Symptoms of Narcolepsy
We will explain in detail the common symptoms of narcolepsy: sleep attacks, cataplexy (loss of muscle tone), hypnagogic hallucinations, and sleep paralysis.
1: Sleep Attacks
As the name suggests, a person is suddenly overcome by an intense urge to sleep in attacks. They may fall asleep even in situations where dozing off would normally be unthinkable, such as during a meeting, an exam, or a first date, which can significantly disrupt daily life and lead to dangers such as injuries.
This is the most basic symptom for people with narcolepsy, and a characteristic feature is that even a short nap of a few minutes to about ten minutes can often completely relieve the sleepiness.
2: Cataplexy (Loss of Muscle Tone)
Emotional triggers such as laughing, anger, surprise, tension, or strong emotions can suddenly cause a loss of muscle tone in part or all of the body. This loss of muscle tone, such as "knees giving out," "dropping objects," or "difficulty speaking," can be followed by falling asleep.
While not all individuals with narcolepsy experience this symptom, it is an important diagnostic criterion for narcolepsy.
3: Hypnagogic Hallucinations
This refers to experiencing very vivid and realistic dreams immediately after falling asleep. Individuals with narcolepsy may still believe they are awake when they experience these hallucinations, which are characterized by sensations such as "people or animals being nearby," "being touched," "feeling something pressing down on them," or a combination of visual hallucinations and a floating sensation as if flying.
4: Sleep Paralysis
This is a phenomenon where the entire body is paralyzed for several seconds to a few minutes at the onset of sleep or upon awakening, making it impossible to speak or move freely. In Japan, it is called "kanashibari." Medically, it is known as "recurrent isolated sleep paralysis," and it is a type of parasomnia associated with REM sleep (a state where the body is resting but the brain is active).
It is characterized by anxiety and distress at the onset of sleep, and sleep paralysis can also be accompanied by hypnagogic hallucinations. While it is not a supernatural phenomenon and can occur in healthy individuals, it mostly happens upon awakening in the early morning and rarely at night upon falling asleep.
Difference from Hypersomnia
Hypersomnia is a type of sleep disorder where excessive daytime sleepiness occurs despite getting sufficient sleep at night.
Even in situations that require concentration, one may doze off, and once dozing off, they may sleep for more than an hour or fall into such a deep sleep that an alarm clock cannot wake them. However, a key characteristic is that the urge to sleep is generally not strong enough to be irresistible.
The cause of onset is still unknown, but brain dysfunction affecting sleep and wakefulness regulation has been suggested.
Often, one does not feel refreshed upon waking up, and may fall back to sleep multiple times before fully waking up, or experience a state called "sleep drunkenness," where they remain groggy and have blurred memories. Some people also experience symptoms such as dizziness, lightheadedness, and headaches.
If sleep is not restricted, it is said that people often sleep for more than 11 hours a day. Also, symptoms often persist chronically for a long period, so one may sleep for 16 to 18 hours daily for several months.
While not always definitive, the main differences between hypersomnia and narcolepsy include the following points:
Narcolepsy
- Naps are short (under 30 minutes)
- Unable to resist sleepiness, falls asleep
- Total sleep time per day is normal
- REM sleep tends to occur at sleep onset
- Cataplexy (emotional loss of muscle tone) is observed
Hypersomnia
- Naps are long (can last over an hour)
- Sleepy but can resist napping
- Total sleep time per day is long (typically over 11 hours)
- REM sleep is unlikely to occur at sleep onset
- No cataplexy (emotional loss of muscle tone)
Characteristics of People Prone to Narcolepsy
There are several characteristics of people who are prone to narcolepsy.
Highest prevalence among Japanese people
While narcolepsy occurs in all ethnic groups, Japanese people have the highest prevalence rate worldwide. The prevalence among Japanese people is generally said to be about 1 in 600.
Peak onset age is 14 to 16 years old
The onset age is after 5 years old, with a high incidence between the ages of 10 and early 20s, and the peak is said to be between 14 and 16 years old. Furthermore, there is considered to be no gender difference in the onset of narcolepsy.
Family members with narcolepsy
Although many aspects remain unclear, research suggests a genetic component. Therefore, if a parent or sibling has narcolepsy, an individual is considered more likely to develop it.
Coping Strategies for Narcolepsy
Here are some coping strategies for when narcolepsy develops.
Medication-based Improvement
There are mainly two types of medications for narcolepsy: "central nervous system stimulants" and "tricyclic antidepressants."
Central Nervous System Stimulants
A basic symptom of narcolepsy is "sleep attacks," where a person is suddenly overcome by an intense urge to sleep during the day and falls asleep.
People who experience "sleep attacks" take the central nervous system stimulant "modafinil" once in the morning. The effect lasts for about 12 hours. Side effects of modafinil often include headache at the beginning of administration, followed by palpitations, nausea, and loss of appetite.
However, compared to other psychostimulants, it has less dependence and milder side effects, and it is said that these symptoms often gradually lighten.
Tricyclic Antidepressants
In addition to "sleep attacks," people who experience "cataplexy," which is triggered by emotional responses, take a small amount of the tricyclic antidepressant "clomipramine" once a day, in addition to modafinil. The main side effects include constipation, dry mouth, and blurred vision. Starting with a small dose and gradually increasing it over 1 to 2 weeks can help reduce side effects.
Lifestyle Improvement
Reviewing lifestyle habits is also important in the treatment of narcolepsy. It is crucial to maintain a regular routine and get sufficient sleep at night. Additionally, actively taking short naps during the day can be effective, so it is recommended to plan 15-minute naps every few hours if possible. Moderate caffeine intake is also considered beneficial.
What department should I visit at the hospital?
For sleep disorders, it is best to consult with a sleep specialist. The Japanese Society of Sleep Research publishes a list of certified sleep medical specialists and specialized medical institutions, so please look for one near you.
Japanese Society of Sleep Research - Sleep Medicine Certification List
However, the number of sleep specialists and specialized medical institutions with sleep clinics is not very large. There are even prefectures without any certified doctors or institutions. In such cases, which department to consult depends on the symptoms and causes.
Since narcolepsy is caused by abnormalities in neurotransmitters in the brain, neurointernal medicine is suitable. If there is no neurointernal medicine nearby, psychosomatic medicine is also acceptable.
If you suspect "hypersomnia," where you feel sleepy all day and are overcome by an intense urge to sleep during the day despite getting enough sleep at night, then internal medicine, psychiatry, or neurointernal medicine would be appropriate.
Additionally, since hypersomnia may be caused by respiratory or brain function issues during sleep, pulmonology or psychosomatic medicine should also be considered.
If you feel that stress is causing your sleep disorder, psychiatry is appropriate. If your sleep disorder is causing adverse effects on your body (such as fatigue, daytime sleepiness, decreased concentration), you should consult psychosomatic medicine.
If you have trouble sleeping but it does not affect your mind and body, you will often visit internal medicine, so if in doubt, it is recommended to visit internal medicine. Also, if you are hesitant to visit psychiatry or neurointernal medicine, start by visiting internal medicine or psychosomatic medicine.
Focus not only on sleep duration, but also on sleep quality
For busy modern people, it can be difficult to get long hours of sleep every day. Moreover, even if you sleep for a long time, if the quality of your sleep is not good, you cannot fully recover from fatigue. Visualize your current sleep state and use bedding that suits you to get satisfying sleep. If you still find yourself being overcome by a sudden urge to sleep during the day, consider consulting a medical institution.
【Reference】
Ministry of Health, Labour and Welfare: "Narcolepsy | e-Health Net (Ministry of Health, Labour and Welfare)"
