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  • When you think of narcolepsy, you probably think of people falling asleep at seemingly

  • random times, but it's actually much more than that.

  • It causes hallucinations, insomnia and sleep paralysis and can be triggered by moments of joy.

  • Oh, and the key to understanding it came from studying man's best friend.

  • Narcolepsy is a neurological disorder where your brain loses its ability to control its sleep-wake cycle.

  • This includes symptoms like cataplexy, a condition that causes uncontrollable muscle weakness

  • or paralysis which is often triggered by excitement or laughter, and hypnagogic hallucinations,

  • which is basically when you start to dream before you fall asleep.

  • That's great.

  • It would be white wine.

  • Hello my name is Emmanuel Mignot, I'm a professor at Stanford.

  • I'm a medical doctor and a researcher and I've been working for 30 years on a sleep disorder called narcolepsy.

  • Narcolepsy is a very strange disorder...

  • So initially people thought it was even a type of seizure.

  • But then when people looked they said no, it's not seizures, they are more sleeping.

  • But narcolepsy isn't really about falling asleep, it's about not being able to stay

  • awake - and the role of a specific neuropeptide made in a very small region of the brain.

  • The region that's called hypothalamus which is just above the optic nerve.

  • So very important, very primitive part of the brain that regulates sleep, appetite, very basic physiology.

  • And these cells that produce hypocretin are all there.

  • Hypocretin, also known as orexin, is a neuropeptide that is responsible for keeping you awake.

  • Once released, hypocretin travels throughout the brain activating other cells, like those

  • responsible for creating things like dopamine, histamine, serotonin and norepinephrine.

  • These brain cells then start to fire more, releasing their respective chemicals which,

  • in turn, further stimulate your brain.

  • And the other thing it does is and that's a little bit less understood but it can also control your dreaming.

  • So is that when this chemical is absent, dreams come too strongly and too fast.

  • And that's why you have all these weird symptoms of dreaming too much and the dreams are almost

  • real and sometimes you are paralyzed at the wrong time because you are paralyzed during dreaming.

  • So the two main function of this chemical is: one is to stay awake voluntarily and the

  • second one is to control your dreams so that your dreams don't come too fast into wakefulness.

  • And this chemical is very important...and when it's not there you have narcolepsy.

  • It took me 10 years to figure out the cause of narcolepsy in terms of losing the hypocretin cells.

  • Then it took me 15 years to figure out why the cells were missing.

  • This is the Pandemic H1N1/09 virus, but you may know it as the swine flu.

  • Dr Mignot and team noticed that during the 2009 swine flu pandemic, there was a significant uptick in narcolepsy cases.

  • And that I have to say we discovered by chance that it seems to be the flu that triggers this abnormal reaction

  • In fact we discovered that there is a piece of this 2009 swine flu that looks very much like hypocretin.

  • And then instead of attacking just the flu the cells start to attack hypocretin and then

  • it kills the cells that produce it.

  • And then once the process is started then it starts to be more and more inflamed and

  • then it kills the hypocretin cell thinking is the flu infected cells and then you don't

  • have anymore hypocretin cells and then you have narcolepsy for the rest of your life.

  • The immune system attacking hypocretin producing cells is why many people categorize narcolepsy

  • as an autoimmune disease.

  • But this response doesn't happen to everyone who gets the flu virus.

  • In fact, I like to say that to develop narcolepsy, you have to have a series of bad luck.

  • You know because really your immune system has to be primed a certain way and you have

  • to get the flu at a certain time together with a certain immune background to genetic

  • background to really develop narcolepsy.

  • So it's like a perfect storm to develop narcolepsy.

  • But humans aren't the only ones to develop narcolepsy.

  • It can affect dogs and as well as horses and bulls.

  • In fact, by studying narcolepsy in dogs, Dr Mignot and others were able to initially make

  • the connection between hypocretin and staying awake.

  • And at the end you know one breakthrough was actually which found a family of dachshund with narcolepsy.

  • I still remember the dog.

  • It was Fritz.

  • Narcolepsy in dogs is a genetic disease, so researchers were able to map the mutation

  • that caused narcolepsy in dog families, notably in Fritz, and found a very important mutation.

  • And then finally we discovered that this gene was a mutation in a receptor for a chemical called orexin, or hypocretin.

  • From there Dr Mignot and his team were able to focus their study of narcolepsy in humans

  • and eventually come to their breakthrough connecting it to the hypothalamus and the swine flu.

  • Fritz was really key.

  • Thanks Fritz...good dog.

When you think of narcolepsy, you probably think of people falling asleep at seemingly

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Here's What Causes Narcolepsy

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    Jerry Liu   に公開 2019 年 07 月 20 日
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