- [Narrator] Humans can teach their bodies to do amazing things, like memorize the order of 59 packs of playing cards. Yes, that actually happened. Or run 100 meters in less than 10 seconds. What about things your
body does by accident? These are the things you never celebrate. These are the things that
sometimes embarrass you, the things you don't want to talk about, but are totally natural. Let's lift the lid on your
body's automatic activities. Here's our top 10 things your body does, but you can't control. (light music) - Amazing! - [Narrator] Number 10, forgetting why you walked into a room. This is something we rarely
talk about, but we all do it. No, not that. I'm talking about walking
into a room, and then totally forgetting about
the purpose of your journey. The reason for this phenomenon? Apparently, it all comes
down to the doorway, and hence has become known
as the doorway effect. Scientists at the University
of Notre Dame found that people were three times more likely to forget a piece of
information if they had to walk through a doorway
before remembering it. What happens is your brain
sees as doorway as a boundary. In other words, what happens before the doorway can stay there. This is your brain in Vegas, and the first entry in our top 10. Number nine, gleeking. No, this isn't bursting into song and dance at any opportunity. It's when you accidentally
shoot a gush of saliva from under your tongue,
like a snake spitting. Gleeking as a word has been
around since the 1500's, and even crops up in
Shakespeare's Henry V. It happens when saliva
builds up in your mouth. Maybe because you've eaten something sour. When you yawn, you may
accidentally squeeze the salivary gland under your tongue,
and whoosh, there it goes. As it's one of the grosser
things your body does without knowing, it definitely
deserves a spot in this video. Number eight, blushing. We've all been there, you're
in a difficult situation, and your cheeks go a dark shade of red, showing the world that you're not okay. Is it embarrassment, anger, or just your body's way
of handling pressure? Charles Darwin called blushing, "the most peculiar of human expressions". And the reason for it is
still unknown to this day. Some scientists believe
it developed as a way of submitting to more
dominant people in society. Others believe it's an
internal reaction to anger, or a way for people to find
out if someone is lying. Either way, there may be a silver lining for those who blush. A team of Dutch psychologists tested 130 undergraduate students at
the University of Groningen and discovered that
people are more likely to forgive and view favorably
someone who has committed an embarrassing act if he
or she is visibly blushing. Don't think this is a get out
of jail free card, though. It's unlikely to work all the time. Number seven, hypnagogic jerk. This is the technical definition for something you've most likely
wondered about in the past. It refers to when you shudder and twitch as you drift off to sleep. Sometimes you jolt so violently,
it causes you to wake up. It can be pretty unsettling, especially if you're
watching someone else do it. Hypnagogic means the period of time when you're falling asleep, by the way. Scientists aren't 100% sure
why these jerks happen, but there are a lot of theories. Some believe it's caused by stress, or an unhealthy lifestyle. Another interesting one is that your primate's brain mistakes
falling asleep for falling out of a tree, so
jerks you awake to take action. Studies claim that 70%
of people experience hypnogogic jerks when they fall asleep. Have you ever noticed yourself doing this? Number six, yawning. (yawns) Yawning, just say the
word and it sets me off. It's one of those things we all do, but we hate to be caught doing it. We also hate it when other people yawn in front of us, but why do you yawn? Scientists used to believe
it was to take more oxygen into your lungs, and to keep
your body awake and alert. They now believe that yawning is your body's way of cooling down the brain. Yawning brings in a burst of cold air which is carried to the brain,
pushing out excess heat. That's why you feel more
alert when you yawn. Why is yawning contagious, though? That we don't know. (yawns) Number five, being ticklish. If you're a ticklish
person, you're probably twitching just thinking about it. So why do we do it? Evolutionary biologists and
neuroscientists believe that we laugh when we are tickled
because the part of the brain that tells us to laugh when
we experience a light touch is also the same part that tells us to expect a painful sensation. There are numerous hypotheses
attempting to explain this. In the late '90s, a scientist
called Christine Harris did a lot of ticklish experiments,
and came up with one idea. Tickling evolved to help
children develop combat skills. When you tickle a child,
they'll try to run away, teaching them how to evade an attacker as painlessly as possible. Meanwhile, they're laughing and smiling, so you can just carry on doing
it, reinforcing the practice. So, keep tickling kids. Teaches them self defense, apparently. Number four, hiccups. We all get the (hiccups)
hiccups from time to time, although hopefully not
like Charles Osborne from Iowa, who hiccuped for 68 years, making the Guinness Book of Records. Again, no one knows why you hiccup, and I'm sure if they did,
Charles might wanna know. Some scientists believe
it evolved as a way for babies to expel air from their stomachs so they could take on more milk. Another study in 2012
argued hiccuping starting even earlier with our amphibian ancestors. Amphibians use a technique similar to hiccuping to push water over their gills. Among the crazy techniques
to try and get rid of them, no one knows how you get
rid of hiccups either. Do you know a way? Number three, shivers down the spine. It happens to all of us. You're in a dangerous or
a stressful situation, and you feel a cold chill go
down the length of your spine. Your hair may stand on end, and
you may also get goosebumps. This happens because in
times of intense pressure, your brain releases a burst of adrenaline to help the brain deal
with this situation. This is partly why many people love being scared shitless, the nutcases. However, music can also make you feel shivers down the spine. This is because when you
hear a piece of music that affects you
emotionally, your brain is flooded with dopamine, the same chemical that is released by sex, and good food. Number two, placebo effect. You're sick, the doctor gives you a pill and tells you you'll be fine. You get better. However, you find out later that the pill had no medication
in it, it was just sugar. What's happened? That, my friend, is the placebo effect. You can trick yourself
into getting better. In 2010, a survey showed
that 56% of doctors had prescribed placebos to their patients. So, why does this work? One theory is that we really
want to show our doctor how great we are, so our unconscious mind suppresses any sickness we may have. People have also used the
placebo effect to sleep better, lose weight, and boost their productivity. The placebo effect is a
real world demonstration of your brain's awesome power. Number one, dreaming. Where would we be without dreams? Our nights would be much duller, and songwriters would struggle
for things to write about. But what do we know about dreaming? Well, we know you dream
during the rapid eye movement, known as REM, section of your sleep. REM usually happens about 70 minutes after you fall asleep, and
lasts 20 to 30 minutes. Typically you go through REM
sleep three or four times during a normal night's sleep. Your brain is active, and your eyes, guess what, move rapidly. Apart from that, we actually
don't know that much. People have tried to analyze
dreams since time began, but still, we don't know why we see a series of images and
situations when we sleep. Sigmund Freud thought dreams were our unconscious desires
playing themselves out. Some experts believe it's
our brain tidying itself up, and emptying itself of useless thoughts. Then, there are also lucid
dreams, where you're aware that you're dreaming, and
can control your dreams. There are even studies
of monitored patients who were rigged up to
EEGs, and observed to be in deep sleep despite being
able to signal to the scientist that they were awake with
a twitch of their eyelid. If you'd really like
to have a lucid dream, because who wouldn't, just
imagine what you could do, then there are several
suggested approaches. Unfortunately though, the science behind this remains inconclusive. So there we are, 10 automatic
bodily functions that have made us blush,
laugh, dream, and more. Do you agree with any of the explanations behind these uncontrollable habits? Leave a comment to let us know. Thanks for watching, and
subscribe to Be Amazed.
