Science of sleep.
Transcriber: Rhonda Jacobs
Reviewer: Eunice Tan
In 1964, Randy Gardner,
some college friends
and a university professor,
Professor William Dement,
decided to go for the world record
of days without sleep.
After day two,
Randy could barely hold his eyes open,
and he couldn’t repeat
simple tongue twisters.
His friends were falling asleep
leaned up against the wall.
By day three, he was
uncoordinated and moody.
By day five, he was hallucinating.
He managed to make it
to 11 days and 25 minutes
before he was rushed
to the local naval hospital,
where he spent, for the first night,
14 hours asleep,
and spent the majority of that time
in deep and dreaming sleep -
these are your restorative sleep states.
Moving on to other research,
Williamson and Feyer show us
that if you spend around
15 to 19 hours deprived of sleep,
you will behave as if
your blood alcohol level is 0.05.
That’s drunk.
Your reaction times
will be 50 percent slower,
and your accuracy will be abysmal.
If I got you drunk
and I gave you your keys,
would you drive home?
At the end of a long shift at work,
if I gave you your keys,
would you drive home?
Now, in one of these situations,
you’re going to be arrested,
and in the other situation,
you’ll be thanked for your time and paid.
The answers to these questions
tell us a lot about
how we as a society value sleep,
and as individuals, how we value sleep.
We know from the research
that if you don’t get around 7 to 9 hours
on average of sleep per night as an adult,
it’s going to impact
your mood, your health,
increase your accident rate,
and it’s less likely
that your marriage will work out.
(Laughter)
The relationship between sleep
and mental health
is intimately and
bidirectionally intertwined.
Traditionally, we thought
that if you had sleep symptoms,
it was a symptom
of your mental health problem.
However, we now know that poor sleep
wreaks absolute havoc
on your neurotransmitters
and your stress hormones,
making it really hard
for you to think straight
and for you to maintain a good mood.
The stats on sleep and health
tell us exactly the same story.
If you have disturbed sleep,
you’re more likely to have
a cardiovascular event,
get diabetes, get cancer.
And if you’re an under-sleeper,
that’s a person who sleeps
for six hours or less,
or an over-sleeper,
that’s a person who sleeps
for 10 hours or more,
you’re at higher risk
of all-cause mortality.
We are not going to work
ourselves to death;
we’re going to wake ourselves to death.
However, each night all of you hold a key,
a magical pill to help you
rewire and heal your brain.
Even Randy Gardner held that key,
because when Randy went to sleep
and he spent the majority of his time
in deep and dreaming sleep,
he was healing.
During deep sleep,
you open up your brain’s dedicated
waste clearance system -
this is your glymphatic system.
And this system,
made up of all these beautiful little
glial cells that kind of look like stars,
pulse with your cardiovascular
system at night time.
The point to this system is to wash
the metabolites out of your brain
and bring fresh supplies in
so that you can work well the next day.
We know that in people
where they have disturbed sleep
or their glymphatic system can’t work well
because of cardiovascular
problems or older age,
we don’t wash these metabolites
out of our brains so well.
They build up in our brain,
and it puts us at a seven to 27 percent
higher risk of cognitive dysfunction
and of dementia in later life.
But I say to you
that you are waking yourself to death
but you can sleep yourself well.
The other sleep state that Randy
spent the majority of his time in
was dreaming sleep.
During the day, you process
hundreds of thousands of events
that prime synapses -
those are the connections
between your neurons or your nerve cells -
that need further processing.
When you go into dreaming sleep,
your brain processes
those primed synapses further,
creating proteins and laying down
long-term memories.
The other thing that happens
is that you prune away the synapses
that you don’t use very often,
and that makes your brain
more effective and more efficient.
So what I want to talk to you about today
are three locks on your sleep
and three keys for you to unlock that.
And you can start these changes tonight.
Lock number one:
dirty bedtime habits.
(Laughter)
In the 1890s, there was a Russian
behavioral scientist called Pavlov,
and he took some dogs
and some bells and some meat.
And every time he’d ring the bell,
he would present the dog with some meat,
and that would make the dog salivate.
With enough pairings
of the stimulus, which is the bell,
with the reward, the meat,
he could make the dog salivate
just by presenting the bell.
You are an animal,
and so you can train yourself
behaviorally in this way as well.
With enough presentations -
clean presentations -
of the bed with feeling sleepy,
eventually, the bed is enough
to make you feel sleepy.
But they need to be clean presentations.
So that brings you to key number one:
Clean your routine.
If you have a clean routine,
your body learns.
And your body learns
to give you melatonin at night
to make you go to sleep at the same time,
and cortisol in the morning
to make you wake up and feel refreshed.
Now, when we’re talking about
the amount of sleep you get,
we also want quality of sleep.
Keeping that same routine
is what gets you that quality.
When you’re creating
this clean routine tonight,
I want you to think about …
babies.
If you want your baby to sleep,
you’re going to do the same thing
every day by routine.
You’re going to give them
a light and fairly satisfying meal,
and then you’re going to
give them a shower or a bath
because that’s going to help
drop their core body temperature,
which is one of the things
we do when we go to sleep.
Then you’re going to read them a book
and take them to a room where it’s dark
and comfortable and quiet and cool -
around 19 to 20 degrees Celsius.
And you’re going to repeat this pattern
because anyone who’s had a baby
knows that if the baby
sleeps well, you sleep well.
So you need to think about yourself
in this same way.
If you treat yourself with the routine
like you would a baby,
you will also sleep well.
If you take nothing else
away from this talk today,
I want you to keep the same wake-up time.
Because the research shows us
that is the critical thing you need
to keep exactly the same,
with about a half hour change either side,
to make sure that you sleep well,
with good quality.
That takes us to lock number two.
Lock number two is overthinking.
Overthinking is not great for your sleep.
And that’s because of how our brain
operates at nighttime.
We are a diurnal species -
that means we’re awake during the day
and we’re built to be asleep at nighttime.
So at nighttime,
your executive functions -
this is a system in your brain
that’s responsible for problem-solving
and for directing your attention -
shut off.
And your default mode network -
this is a network inside of your brain
that’s responsible for things
like daydreaming and self-reflection -
that turns on.
With this pattern
of turning off and turning on,
unfortunately you cannot trust
your thinking at nighttime.
We know that from statistics,
we have a much higher risk,
or people who are at risk of engaging
in self-harm and suicide behaviors
are going to do it at nighttime.
And one of the contributing factors
is this pattern of things that turn off
in our brain and things that turn on.
You cannot trust
your thinking at nighttime.
Tell me this:
Has anyone had the experience at nighttime
where you wake up
in the middle of the night
with an absolute aha moment?
Yeah? Or thought, Oh my gosh,
absolute disaster.
Only to then wake up in the morning
and realize it was complete waffle.
Yeah? I think most of us
can relate to that experience.
That is you experiencing
parts of your brain turning off
and parts of your brain turning on.
So that takes me to key number two.
When you go to bed,
put your thinking to bed.
Now, I’m going to say that,
and then there’s going to be
a lot of people in the audience
that are thinking, That’s not as easy
as you’ve said it to be.
But you will all be familiar
with this non-pharmacological,
non-invasive technique
that is actually fabulous
for helping you direct your thinking
to where you want it to go,
and that’s called
meditation and mindfulness.
Now, this has come
out of the realm of the esoteric,
and we now know from research
that if you practice this
for 15 minutes a day,
you will get the health benefits
and also you will develop
a thing called meta-awareness.
Meta-awareness is the capacity
to think about your thinking.
Mindfulness and meditation, if practiced,
it’s a bit like you’re
weightlifting for your brain.
Now, you remember I said
your executive functions go off
and your default mode network goes on.
If you practice mindfulness
and meditation,
you’re able to catch this mind-wandering
and bring your brain back
to where you want it to be focusing on.
Mindfulness and meditation
are the antithesis
to mind-wandering at nighttime.
So lock number three.
Lock number three is your technology
is too smart for your biology.
Now, most of you will have
one of these beautiful little devices
in your pocket or your handbag.
A lot of you probably take them
to bed with you.
They come in around that kind of shape.
And they allow your boss to come into
your bedroom with you at 9:00 at night
and tell you that the Friday deadline
that was due for Friday
is now due tonight.
They tell you that your best friend can
come into your room at 3 AM in the morning
and say that they’ve made
the most amazing cheese toastie.
This is fantastic because it means
that we’ve got our friends and our bosses
and everyone’s so available.
It’s not great for your sleep,
unfortunately.
There’s two theories
on why this might be the case.
The first theory is that
the content on these devices
is incredibly stimulating or stressful.
And you’ll remember that I said
that one of the hormones
you release to wake up is cortisol.
If you are stimulated or stressed,
one of the hormones
that you will release is cortisol.
So, simple. Not great for sleep.
The other reason, and the evidence
is a little equivocal for this one,
is that the wavelengths of light
on these devices is blue light.
And so that means
it’s the same wavelength of light
as you get exposed to during the day.
That light goes in through your eye
to your suprachiasmatic nucleus -
there’ll be a test on this at the end -
(Laughter)
and that is your master clock.
The suprachiasmatic nucleus
resets your entire body clock
to say it’s daytime.
Again, not so great for sleep.
So that brings us to key number three.
Key number three is at nighttime,
put the tech down
and let your biology do its job.
If you want to sleep well,
you need to have good boundaries
around your tech use.
And this goes for you
and your kids as well.
The research shows us
that if you allow your kids
to have free rein on their devices,
they’re going to push their bedtime back,
they’re going to want to wake up
earlier in the morning,
and they possibly will have a higher risk
of mental health problems as well.
So about two hours before bed,
devices need to go away.
And for yourself, be a role model at work.
Call a work work meeting.
Say that you went
to a TEDx Talk on sleep health
and you now want to be
the sleep health advocate at work.
Make sure that there are work boundaries:
no emails after six,
nothing on the weekends.
Be a role model.
Because we know
that if you want to work hard,
you need to rest harder.
So that gives us three things
for good sleep.
The first is clean your routine.
The second is that overthinking
is the enemy for sleep.
Meditate.
And the third is put the tech down
and let your biology do its job.
I’ve said to you that we are waking
ourselves to death.
But let’s all start tonight
to sleep ourselves well.
Okay, thank you.
(Applause)