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- Hi, I'm Lauren.
- And I'm Ben and this is Brain Stuff.
Okay, Lauren, hypothetical situation.
- Yes, Ben.
- Okay, so let's say that
we're explaining sleep
to an alien race that doesn't sleep.
And here's what we say.
We say, "Oh, hey,
"I'm having a great time
hanging out with you,
"alien civilization, but pardon me.
"I have to go be
unconscious for eight hours
"and have vivid hallucinations."
- Shut down many of my body systems
in order to completely lose
track of time and space.
- Yeah.
- Yeah, that sounds cool, right?
I mean, that's okay.
- I think it's kinda weird.
So here's the thing.
Everybody's gotta sleep,
yet we still don't know exactly why.
But the two of us are gonna do our best
to crack the case today, right?
- Oh, that's right.
We'll review some
theories for why we sleep,
what happens when we sleep,
and what happens when we don't.
- And even though we don't
100% know why we sleep,
there is all sorts of
educated speculation.
The most prevalent is
that sleep gives our brain
a chance to organize
and process information,
possibly through all those weird dreams
that we always tell strangers about.
- Basically, our brain takes
all the sensory stimuli
we received while we were awake
and decides what to keep
and where to file it.
Everything else gets trashed
or turned into delightful
Facebook stories.
- Right, yeah.
And it's even possible that
our ability to learn tasks,
you know, like learning a language
or how to ride a bicycle or
burn down a yacht or something
benefits from sleeping on it, right?
It's a process that's better understood
after our brain reviews and catalogs it.
And while most people would agree
that this memory consolidation
is a valid theory,
it's tough to pin it down
because we all sleep so differently.
- That's right.
And here's another theory.
Sleep gives our bodies
time to rest and repair,
or how about sleep lowers
our energy consumption
so that we can conserve
the meals that we've eaten.
- Yes and other theories delve
into the biochemical
mechanism of the brain.
Lauren, in 2013, a series
of experiments on mice
showed that cerebral spinal fluid
was pumped around their
brains while they slept,
expelling waste like molecular
detritus and toxic proteins
into their livers for breaking down.
- So do we sleep just to flush the toilet
on our cerebral commodes?
And thanks for giving me
the toilet joke, guys.
Well, okay, so other sleep researchers
were skeptical of the study
that Ben just mentioned,
pointing out that there are
some really big differences
between a mouse's brain and a human's.
- So while the answer to why we sleep
isn't written in stone,
we do all know that when we sleep,
both our mind and our body feel refreshed.
But how much sleep do we actually need
to feel good in the morning?
- Well, most of us need between
seven to nine hours a night
but that changes during
different points of your life.
For example, a newborn baby
might sleep 20 hours a day.
But by the time they're three months old,
they recognize that circadian rhythm thing
of sleeping at night and waking
up in the morning hopefully.
When you're older, like
senior citizen older,
you can probably get by on like
six to seven hours a night.
- And regardless of
how long you're asleep,
you must experience both
REM and non REM stages
to sleep well.
That's rapid eye movement,
not the band from Athens.
A normal person spends
25% of their sleep in REM
with each session lasting
between five and 30 minutes.
- During this time, our brain speeds up.
Our eyes and face might twitch in REM
because we're dreaming.
We need about 90 minutes
to complete a full cycle
of that REM and non REM sleep.
- And researchers think
this cycles ties sleep
back to our ability to
process task and memories.
Recordings show that
many of the same neurons
that fire when we're learning
are reactivated during REM,
consolidating these patterns
into permanently wired connections.
- But don't sleep too much.
More than eight hours can lead to
or signal depression or
even precipitate Parkinson's
or heart disease.
Of course, if we don't sleep,
that's a whole other mess of problems.
- Right, yeah.
Rats will drop dead if they go
more than three weeks without sleep.
And we, as humans, not
just you and I, Lauren,
get lethargic and cranky
and foggy headed at first.
It's almost like we're intoxicated.
We might even nod off into
micro sleep for a few seconds.
This is what happens after one
or two nights without sleep.
By day three, we start hallucinating,
lose the ability to recognize reality.
- And that's if you're really pushing
the boundaries of sleep.
Simply failing to get enough sleep
is connected to obesity,
high blood pressure,
a weakened immune system, heart disease,
cancer and diabetes.
- So we might try to get by on caffeine
or nicotine or other stimulants,
and yeah, alcohol is a good sedative,
but it doesn't actually
provide the sleep we need
for all that neural processing.
So in the words of the immortal
poet Chris Ludacris Bridges,
if you're tired, be quiet and go to sleep.
- I bet you've had trouble sleeping
or at the very least hate
sleeping as much as we do.
Tell us if your problems
with sleep line up
with what we've shared
with you in this video.
- And go ahead and like, subscribe,
leave us a comment below where
you can tell us this stuff
and you can also check our
more videos on the side.
These are pretty good, right?
- Yeah, I like that one.
- Oh, yeah, well that was,
that's one of the best ones.
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