Imagine suddenly falling asleep while having a conversation with someone or, worse, while driving, though you have had a good sleep the night before. Narcolepsy can mean exactly that and more. If you have this neurological problem, your brain can’t properly regulate your pattern of waking and sleeping. In people with normal sleep cycles, rapid eye movement sleep (REM, the dream phase) occurs after around 60 to 90 minutes, and the muscles go limp so that they don’t act out dreams. But in people with narcolepsy, REM starts within 15 minutes of going to sleep. Also, dream activity or muscle weakness can set in during wakefulness.
It can lead to symptoms like excessive sleepiness during the day, sleep attacks where you suddenly fall asleep, sleep paralysis, and vivid hallucinations while falling asleep or waking up. You may also experience cataplexy or temporary muscle weakness and loss of muscle control. And as you can imagine, narcolepsy may interfere with your social, professional, or academic activities and disrupt your daily life.1
So what exactly causes narcolepsy? While we don’t yet completely understand this condition, researchers believe that a combination of factors may play a role here.2
1. Low Levels Of Hypocretin
Almost everybody who suffers from narcolepsy and experiences the symptom of cataplexy has very low levels of a neurotransmitter known as hypocretin, which controls REM sleep and promotes wakefulness. However, hypocretin levels are typically normal in those who suffer from narcolepsy without cataplexy.
2. Malfunctioning Immune System
When your immune system is functioning normally, it releases antibodies that protect you by destroying harmful germs and toxins. But, sometimes, the immune system mistakenly attacks healthy tissues and cells. This faulty response of the immune system is known as an autoimmune response and it has been found to play a role in narcolepsy. Some people with this condition make antibodies against trib 2, a protein made in the same part of the brain that makes hypocretin. The immune system then attacks brains cells which have hypocretin, causing low levels of this neurotransmitter.
3. Variation In A Particular Gene
Scientists have identified many genes that can have an impact on your risk of getting narcolepsy. The gene known as HLA-DQB1, which contains instructions required for making a protein critical for the functioning of your immune system, is especially important. This gene is from a family of genes known as the human leukocyte antigen (HLA) complex which helps your immune system differentiate between proteins made by germs and proteins present in your own body. Many variations of the HLA-DQB1 gene occur normally, which allows your immune system to respond to a range of proteins from foreign organisms. One variation known as HLA-DQB1*06:02 has been linked strongly with narcolepsy, especially when it occurs with cataplexy and low levels of hypocretins.
4. Family History
Although most cases of narcolepsy occur in people with no family history of the condition, about 10% of people who have narcolepsy with cataplexy have a close relative who suffers from this condition.3 And it is estimated that people whose parents, children, or siblings have this condition have a 40% greater chance of developing it when compared to the general population.4
5. Brain Injury
Narcolepsy can sometimes be caused by a traumatic brain injury, brain tumor, or diseases like multiple sclerosis, or encephalitis which affect the brain. This happens due to injury and damage to areas of your brain that are responsible for regulating REM sleep and wakefulness.5 6
6. Infections Like Swine Flu
Infections such as a streptococcal infection or swine flu have been found to trigger narcolepsy in some people. Researchers have found a tendency toward high levels of antibodies against streptococcus, the bacteria which is responsible for strep throat immediately after the onset of this condition. This suggests that strep and other infections may trigger an autoimmune response against hypocretin neurons.7
7. Hormonal Changes
Hormonal changes such as those experienced during menopause or puberty may work as a trigger for narcolepsy in some people.
8. Psychological Stress
Psychological stress may also trigger narcolepsy in some people. One study looked at the occurrence of stressful life events in the year before the development of narcolepsy and found that a significantly greater proportion of people with narcolepsy reported stressful events than the control group. Narcoleptic people also attached a greater weight to the events they reported in comparison to the control group.8
9. Abrupt Disruption Of Sleep Patterns
Suddenly changing sleep habits, whether due to jet lag, shift work, or tending to a baby or a sick person, may also trigger narcolepsy in some people.
10. Environmental Toxins
Some research indicates that narcolepsy may also be triggered by environmental toxins. Heavy metals, weed killers, pesticides, and secondhand smoke can all work as triggers.9
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