Say you've been napping, like between classes, or after a long night out,
or, I don't know, after broadcasting on YouTube for 48 straight hours to raise money for charity.
Now, imagine you waking up, and suddenly you discover that you can't move.
You want to speak, but you can't;
you're mind is acutely aware of what's happening, but you are powerless to get your body to do anything.
It may last a few seconds, it may last a few minutes, in rare cases it can last more than an hour
it's called Sleep Paralysis
and you might not have to imagine it
because up to 40% of us have experienced this sleep disorder at some point in our lives.
I am one of them.
We don't like to think about the bad things that can go on while we're in dreamland
just as we hate the disorders that keep us from even falling asleep
Hello, Insomnia.
But even though we've talked a lot on this show about the science of sleep
Why we need it
Why we dream
and where dreams come from.
There is a whole other polymorphously messed up realm
of human biology that explains what happens when sleeps turns against us.
We can't turn our brains off.
We forget to breathe.
We have waking hallucinations.
Some of us even walk, eat, run, and have entire conversations when we're asleep.
The half-asleep brain is a crazy place
and once you understand it, you may never see the back of your eyelids the same way again.
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When most people think of the things that cramp our sleep style they think, Insomnia.
But defining, diagnosing, and treating this most common sleep disorder can be tricky.
In fact, for a long time, most scientists considered insomnia to be a symptom of another problem
like depression, anxiety, asthma, stress, substance abuse, a traumatic injury
even jetlag
Though, today, insomnia is considered by many to be a chronic disease of its own
that interacts with other medical conditions
So, if you've ever had prolonged trouble falling asleep, or staying asleep
but you don't have any other health issues
then doctors would probably say that you have Primary Insomnia.
If you do have something else going on, like a physical or psychological condition
then you've got Secondary Insomnia.
And most cases of Secondary Insomnia are chronic
meaning it lasts for more than a month.
There are also cases of Acute or short-term Insomnia
which is usually triggered by stress or some specific life event
Whatever the cause
scientists believe these Insomnias are the result of the simple but eternal struggle
between arousal and sleepiness.
More and more research is suggesting that a condition known as Hyper-Arousal
where the nervous system remains in a constant state of alert
may be the main reason for chronic insomnia.
Hyper-Arousal is basically a prolonged version of your body's Fight-or-Flight response
You know that feeling: Your stress hormones are amping up
Your heart and respiration rates increase.
For most people, this response disappears pretty quickly
but for many Insomniacs, it can last all day into the night
and that makes it difficult for the body to relax, obviously.
But what's there to be afraid of once you HAVE dozed off?
Well, Sleep Apnea is one of the more serious disorders, simply put,
is when you're breathing is interrupted while you're sleeping.
Apnea comes from the Greek word for "Want of Breath"
For some people, it happens once or twice per night
in serious cases, it can happen more than a hundred times per hour.
Though relatively common, more than 12 million Americans have it.
The most severe forms of Sleep Apnea can lead to heart failure and stroke.
It's also been linked to diabetes.
One of the more troubling aspects of Sleep Apnea is that the victims don't always realize they have it.
The most common form: Obstructive Sleep Apnea
happens when the muscles at the base of the tongue
and the uvula, that fleshy piece of tissue at the back of the throat
collapse.
If this collapse blocks the airway only partially, then you get snoring
as air tries to squeeze through.
But apnea occurs when the airway is completely blocked.
When this happens, blood oxygen levels drop fast, which in turn tells the brain the breathing has stopped
and that those muscles have to reopen the airway post-haste.
But his whole conversation between your body parts can last from a few seconds to a few minutes,
usually without the person ever waking up.
Needless to say, though, this does not make for very restful sleep.
And there are all kinds of treatments for this kind of apnea,
but most people end up using a Continuous Positive Airway Pressure or CPAP Machine.
It has a mask that fits over the mouth and nose, and gently blows air into the throat
helping to keep the airway open.
Which doesn't sound very restful either.
Another type of disorder: Central Sleep Apnea, is much more rare.
Instead of a physical blockage in your throat that prevents breathing
this is interruption of the brain signals that tell the body to breathe.
Until recently, there were few effective treatments
but scientists are experimenting with a new pacemaker-like device
that sends an electrical impulse to stimulate the diaphragm to breathe during sleep.
Okay, so forgetting to breathe is pretty bad
but sleep disorders get downright dangerous when it comes to sleepwalking.
Partly because, though it affects about 15% of people
it is more common in children between the ages of 3 and 7.
Sleepwalking, also known as Somnambulism, almost always occurs during the first 1/3 of the night.
That's the part of the sleep-cycle we call Non-Rapid Eye Movement Sleep
and it's generally a period of deep sleep characterized by slow brain waves.
While there's no consensus as to what causes this condition
there are a few theories as to why people begin walking, eating, running, even having conversations
while the brain thinks it's asleep.
Some scientists think it's caused by the brain trying to circumvent other stages of sleep
and go directly from deep non-REM sleep to full on wakefulness.
Others point to a chemical messenger in our bodies known as GABA
which normally serves to slow down activity in the brain's motor system.
Turns out that children lack the fully developed neurons that release GABA.
So without a full network of connections in the brain to keep motor activity under control,
it may be easier for young brains to instruct the body to move around while it's asleep.
Which is CRAZY because, have you SEEN how much children MOVE around when they're awake ??
Sometimes the causes of sleepwalking are external and pretty controllable
like sleep deprivation, stress, and drug use.
But scientists have also discovered that some people are genetically predisposed to it.
A study conducted on families with at least four generations of sleepwalkers have traced the condition
to a defective section on Chromosome 20.
And a mother or father who carries this defect has a 50% chance of passing it on to their children.
But this is not the case with Sleep Paralysis
which I experience sometimes.
It's a little weird. Sometimes, even a little scary.
Though I know it's temporary.
But WHY does this happen ?? WHY does my brain and my body decide to freak me out first thing in the morning??
In some cases, sleep paralysis is a symptom of narcolepsy
a disorder that causes people to have an overwhelming need to sleep.
But it also regularly happens to non-naroleptics like me.
The weird feeling of being conscious but unable to move generally occurs as you're falling asleep,
but it can also strike you as you're waking up.
Scientists believe that a main cause is entering REM sleep soon after lying down,
bypassing the stages of non-REM sleep, that normally happens first.
Typically, REM dominates the later stages of sleep, which are also when the most vivid dreams occur.
During this deep sleep, your muscles are essentially paralyzed
most likely, to prevent you from acting out whatever crazy space unicorn riding dream you're experiencing.
Sleep paralysis occurs when you wake up in the middle of all of this
and suddenly you're aware of the fact that moving is impossible.
Recent studies have also found that the same neuro-transmitters that affect sleepwalking
may also cause sleep paralysis.
University of Toronto scientists discovered that both GABA and Glycine switched off the brain cells
that allow muscles to be active during REM sleep.
at least in lab rats.
Now, in the most severe cases of sleep paralysis, victims also experience frightening and bizarre hallucinations.
They can be visual or auditory, and often involve shadows or hearing voices and footsteps
or seeing images of humans and animal figures.
Occasionally, victims will also feel pressure on their chests and have trouble breathing.
Scientists have described this phenomenon as Dreaming While Awake.
To me, I'd prefer to do my Dreaming While Asleep, thank you very much.
And hopefully I didn't make you afraid to go to bed tonight.
Thank you for watching this SciShow infusion.
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This episode comes to you from our latest President in Space: Doug Mestanza
who wants to wish a Happy Birthday to Sashka Korzenska!
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