Hacking your memory -- with sleep

Whether you're cramming for
an exam or trying to learn

a new musical instrument
or even trying to perfect

a new sport,

sleep may actually be
your secret memory weapon.

Studies have actually told us that

sleep is critical for memory

in at least three different ways.

First, we know that you
need sleep before learning

to actually get your brain
ready, almost like a dry sponge,

ready to initially soak
up new information.

And without sleep, the memory
circuits within the brain

effectively become waterlogged as it were

and we can't absorb new information.

We can't effectively lay
down those new memory traces.

But it's not only important
that you sleep before learning

because we also know that
you need sleep after learning

to essentially hit the save
button on those new memories

so that we don't forget.

In fact, sleep will actually
future-proof that information

within the brain.

Cementing those memories
into the architecture

of those neural networks.

And we've begun to discover
exactly how sleep achieves

this memory consolidation benefit.

The first mechanism is
a file transfer process.

And here we can speak about
two different structures

within the brain.

The first is called the hippocampus

and the hippocampus sits on
the left and the right side

of your brain.

And you can think of the
hippocampus almost like

the informational inbox of your brain.

It's very good at
receiving new memory files

and holding onto them.

The second structure
that we can speak about

is called the cortex.

This wrinkled massive tissue
that sits on top of your brain.

And during deep sleep,

there is this file transfer mechanism.

Think of the hippocampus like a USB stick

and your cortex, like the hard drive.

And during the day we're going around

and we're gathering lots of files,

but then during deep sleep at night

because of that limited storage capacity,

we have to transfer those
files from the hippocampus

over to the hard drive
of the brain, the cortex.

And that's exactly one of the
mechanisms that deep sleep

seems to provide.

But there's another mechanism

that we've become aware of

that helps cement those
memories into the brain.

And it's called replay.

Several years ago,

scientists were looking
at how rats learned

as they would run around a maze.

And they were recording the activity

in the memory centers of these rats.

And as the rat was
running around the maze,

different brain cells
would code different parts

of the maze.

And so if you added a tone

to each one of the brain
cells, what you would hear

as the rat was starting to learn the maze

was the signature of that memory.

So it would sound a little bit like.

(bouncy piano music)

It was this signature of
learning that we could hear.

But then they did something clever.

They kept listening to the
brain as these rats fell asleep

and what they heard was remarkable.

The rat, as it was sleeping,

started to replay that
same memory signature.

But now it started to replay
it almost 10 times faster

than it was doing when it was awake.

So now instead you would start to hear.

(bouncy piano music)

That seems to be the second way

in which sleep can actually
strengthen these memories.

Sleep is actually replaying
and scoring those memories

into a new circuit within the brain,

strengthening that memory representation.

The final way in which sleep
is beneficial for memory

is integration and association.

In fact, we're now learning that sleep

is much more intelligent
than we ever imagined.

Sleep doesn't just simply
strengthen individual memories,

sleep will actually cleverly interconnect

new memories together.

And as a consequence you
can wake up the next day

with a revised mind wide
web of associations,

we can come up with solutions

to previously impenetrable problems.

And this is probably the reason
that you've never been told

to stay awake on a problem.

Instead, you're told to sleep on a problem

and that's exactly what
the science teaching is.

(bouncy music)