[Dr Chris] If you know anything
about sleep, you probably know that there are two types.
There's REM sleep, where we dream; there’s deep sleep, where
we don't. And we mostly know that we should try and get more of it.
But scientists like Scott here are discovering there's a huge amount more to it
than that.
[Scott] Well, actually, scientists have demonstrated
that there are five different stages of sleep. It’s achieving
some vital functions that just can't be achieved during wakefulness.
[Dr Chris] And one of those critical functions is to help us remember.
Scott believes that during sleep, the brain selects
which memories to strengthen and which to lose. [Computer] “Rustic.”
[Dr Chris] To show this, I have to create new memories that can be tested later.
So what I'm doing here, what I'm meant to be doing here,
is making associations between the word and the picture.
So here, for example, it says the word “artistic,”
the computer says “artistic” and there’s a picture of a hairdresser.
So I have to make a mental link between “artistic” and “hairdressers”.
This is “military” and there's a potato peeler.
So maybe soldiers carrying potato peelers.
And Scott assures me
this is one of the more interesting experimental psychology tests.
So I shouldn't fall asleep during the test.
“Exotic microwaves.” OK.
And as Scott tucks me in for the world's most
unnatural nap, it's time to let my brain get to work.
Right, am I good to go? [Scott] Yeah, you're good to go.
So, we'll be back in about 90 minutes and just try and relax and enjoy some sleep.
OK?
[Dr Chris] Lovely. All right. I'll see,
I’ll see you in an hour or so. Yeah, and you.
Out.
Been looking forward to this all week. (Snores)
Scott's looking for the phase of sleep he thinks is critical for memory.
OK, so we're seeing some really nice, consistent
deep sleep here, some really nice, consistent slow waves within the EEG.
So I think we're in a good position actually to reactivate some memories.
Um, it's a very simple push of a button.
[Computer] “Surgical,”
“Delicate.” [Dr Chris] To demonstrate
what happens to us every night during slow-wave sleep,
some of the words I learned earlier
are played to me over a loudspeaker to see if I can remember them better. [Computer] “Abandon,” “Extreme.”
And all too quickly,
I'm rudely awoken from my nap.
[Scott] Hey Chris, are you awake?
Hello?
- So the world's worst hotel, isn’t it.
- Yeah. - Like, turn down your electrodes. Then a quick test.
Perfumed...per...I can’t remember.
What's amazing is that it was easier for me
to recall the word associations that were played to me during sleep.
“Alpine”... This fits into Scott's wider results
that show memory performance is much higher in those that sleep
compared to those that take the test without sleeping.
There were quite a few examples of words that popped up
that suddenly, very surprisingly to me, I could remember them.
So, we reactivated a specific word, and then your brain strengthened
the connection between that word and the associated picture.
We think what one of the main things that slow-wave sleep is doing is actually
eradicating all of the irrelevant information that we don't need.
But the other thing that slow-wave sleep is doing is strengthening
the important information. So those memories of things
that we need to remember are being reactivated and strengthened,
so that we're less likely to forget them after sleep.