Hey wake up!
Hey, you!
Yeah, you.
Didn't get enough sleep last night, huh?
I know how you feel.
When you don't get enough sleep, everything the next day just seems so much harder.
Have you ever asked yourself, why is that?
What is sleep, and why do we do it at all?
Let's find out.
All human beings need sleep
It's as important to life as food, water, or air.
You spend about a third of your life sleeping
That means that if you live to a hundred years old,
You'll spend 33 years asleep
That's a lot of time we're wasting, right?
Imagine all the things you could do with an extra eight hours a night.
You could hang out with friends...
Play games
Learn new things
Why even bother sleeping?
Good question.
We still aren't exactly sure what sleep is
Or why we need it
But scientists are trying hard to figure it out
Even if we don't know everything, let's talk about what we do know.
First off, our brains act differently when we sleep.
The millions of tiny cells in your brain, called neurons,
Send thousands of signals to each other every second.
Sometimes those signals line up into patterns, like waves of water on a beach.
Different wave patterns in your brain represent different stages of sleep.
When you first lay down in bed and try to fall asleep, your brain creates fast alpha waves
which are associated with relaxation.
Once you've finished counting sheep, and you start to doze off,
Your brain waves slow down. These are called theta waves,
and they're important for learning and memory.
You're still not very deeply asleep until you sink into what's called slow wave sleep
and boy are they slow.
At this point, the waves are coming only about once per second.
Now, you're definitely asleep.
The next big thing to happen in the sleep cycle is rapid eye movement, or REM sleep.
Just like it sounds, your eyes begin to move very quickly and randomly behind your eyelids.
During REM sleep, it's very hard to wake up,
But your brain waves are actually the most similar to the pattern we see when you're awake.
REM sleep is also the stage of sleep when you dream.
Scientists think dreams happen because your brain is sending so many signals,
just like it does when you're awake,
that it tricks your mind into seeing things, hearing things, and feeling things that aren't real.
You only experience them because of the wave patterns moving through your brain.
Your brain moves through each of these stages of sleep several times a night,
every ninety minutes to two hours.
All four of these stages are very important for your health.
Most likely, our friend here did not get enough cycles of sleep.
So, if we need to sleep every night, our brain must be doing something pretty important, right?
The weird thing is, even though we have theories,
we still haven't quite figured out where sleep came from - or why we need it.
It might be that, millions of years ago,
sleep helped our ancient ancestors survive.
By laying down and not moving for hours at a time,
An animal could avoid getting caught by a predator,
at night, when its vision was worst.
This seems unlikely.
Because when we sleep, we're much less aware of our surroundings,
so, hiding from predators would be harder, not easier.
Maybe we started sleeping because it helped us store energy.
When you had to run around and catch dinner for yourself,
it might have been helpful to shut down your body and use less energy for a while.
This theory also doesn't seem very likely.
Our bodies do use less energy when we're sleeping,
but the difference between being awake and asleep isn't enough to make a big difference.
Probably the most popular and well supported theory about why we sleep
is that our body needs it to effectively grow and repair itself.
Not getting enough sleep is bad for your memory.
That's why it's always important to get a good night's rest before you have a big test.
Scientists think that your brain uses the time your sleeping
to reorganize itself and strengthen the memories it makes when you're awake.
Sleep also seems to be important for healing.
That might be why you want to sleep so much when you have a bad cold.
Your body is better at attacking intruders
And fixing itself when you give it time to rest,
rather than spending all of your energy walking, talking and thinking.
And finally, some very recent findings suggest
that our brain uses the time we're asleep to cleanse itself.
A colorless fluid, called cerebrospinal fluid,
Or CSF, cushions your brain and helps rinse it of debris.
Last year, scientists discovered that
some of the cells in the brain actually seem to get smaller during sleep
allowing more CSF to filter between them.
This means that when you sleep,
your brain might be going into dishwasher mode,
sending lots of fluid between the cracks in your brain to clean out all the gunk that gathers during the day
We're still not completely sure what sleep is,
but we do know that getting enough sleep is very important for our memories, our minds, and our health
So make sure you go to bed early tonight and get plenty of rest!
Good night, sleep tight, and sweet dreams.