Translator: Gisela Giardino Reviewer: Sebastian Betti
You may ask why do we sleep,
or when do we sleep, or how much do we sleep,
or how do we sleep.
The good thing is that science has the answer to all these questions
and it is surprisingly simple.
The answer of science to why, how, when, how much do we sleep,
is very easy:
no idea.
(Laughter)
Wait.
Scientists don't know something as obvious
as what happens to us every night or what should happen every night?
No, we don't know.
And that's wonderful.
In a way it turns all of us into scientists.
We can all experiment with our sleep,
or that of the person next to us,
our friends, our family.
That's also science.
In fact, it's not a full "no idea"; some things we do know.
For instance: why do we sleep?
It seems quite obvious: we sleep because we are sleepy or tired.
Is this actually so obvious?
Let's see, think with me:
when you are on vacation, you are not tired, you do nothing.
Do you sleep less?
No.
And when you work out hard
or you are doing a very demanding physical work,
do they sleep more? No.
So this is not just about being tired, even when there's some of that in it.
There must be more to why we sleep.
We do know something: sleeping is important.
Many years ago, experiments were done
where animals would be sleep deprived, they wouldn't let them sleep.
You know what happened to them?
They died.
And they died in two weeks, as if they wouldn't have eaten.
Sleeping is vital, just as important as eating.
And what else happens while we sleep?
A lot of things:
We grow, the body is repaired, we recharge our batteries.
A lot of things that wouldn't happen if we didn't sleep.
Memories are consolidated.
The worst you can do if you have a test or something important,
is not to sleep to study more, because you will surely fail.
So we know something about the why, but not much.
How about the "when"?
When do we sleep?
We evolved as day creatures.
We have to be active during the day and sleep at night,
locking ourselves up in the cave, away from dangers,
away from what is happening outside.
And why is that?
Because we have this little piece of our brain
that keeps the time and tells the body what time it is.
Our biological clock.
In a way, we are clocks with legs.
Everything we do happens in time, not only in space.
Sleep also occurs over time.
It happens or should happen at night.
But less of this is happening, as we take hours away from our nights
in favor of our waking life.
Since the invention of electric light, that great sleep thief,
we increasingly go to bed later.
Our body is not prepared for that.
In fact, it's true that some people have more or have less need of sleep,
or need to go to sleep earlier or later.
There are morning people, we call "larks".
Some of you are having a very good time now.
Others are "owls", evening people, who are yet quite sleepy now:
"What is this? Where am I?"
(Laughter)
In fact, there are extreme morning people, the extreme larks,
and extreme evening people, the extreme owls.
It can happen every so often,
that an extreme lark meets an extreme owl and they get married.
(Laughter)
In such case, children are a miracle.
(Laughter)
But we have to listen to that clock which tells us when to do things:
when to be awake, when to sleep.
Sometimes it clashes with reality, with society,
with our work schedule, with school.
For example, teenagers are typical owls
and they do everything much later.
You think it's cultural, they go to bed late,
they chat with friends until late night, they go out late.
A lot of it is cultural, but that culture
is based on a biological need, their clock tells them
"do everything later".
What's the problem?
The next day, at what time does school begin?
At seven o'clock in the morning,
which is absurd: the kids are asleep,
literally asleep during the first hours.
We have to work on this:
we should listen to our clock and so should society.
And the "how much"?
How much do we sleep?
How much do we have to sleep?
If I take any of you,
or to anyone to the sleep lab
and I tell them: "Sleep all you feel like"
the average for an adult person is eight hours, twenty minutes.
Eight and a half hours.
Let's see, do you sleep eight and a half hours?
No.
We sleep quite less than that.
It is estimated that we are sleeping an hour less than fifty years ago,
and about two hours less than a hundred years ago.
That's a lot, it really is a lot.
We are finally stealing about two hours of sleep.
What's more, we could make a projection, right?
If we sleep two hours less than a hundred years ago
and one hour less than fifty years ago,
if we draw a line and follow it, more or less by 2758
We won't sleep anymore.
(Laughter)
That cannot happen because sleep is a necessity.
But the need is also of hours of sleep.
And that is for adults.
Teenagers should sleep nine hours or more.
Kids, between nine and ten hours, and they are not sleeping either.
For many reasons, the main one is social.
Society is shrinking the hours we sleep
and that brings us problems.
Screens also harm us because the light coming out of them --
and nobody sleeps alone lately,
we all sleep with a screen in bed, just in case --
it's a light that tells to the clock that is daylight,
therefore meaning: "wake up, all good, keep going."
And surely, the next day we have to wake up.
We sleep less, we sleep bad, we sleep very little.
"And what is the problem?", you may ask.
"I'm doing great, in any case, I catch up during the weekend.
What is the problem with not sleeping well?"
Lots of problems.
One of the problems is that we are going to be sleepy.
Clearly, we will be very sleepy during the day.
You might think: "Not that serious, I can take a nap."
We will be cranky.
Not sleeping changes our mood and that's the least serious issue.
Being sleepy or cranky is not as serious as getting sick.
Not sleeping means illness.
At first, we will get sick due to more infections.
The immune system needs to sleep to protect us from what's out there.
But we are also going to fall ill with metabolic disorders.
We are going to get diabetes.
When this is chronic,
when sleep deprivation turns chronic, diseases show up.
Therefore, not sleeping is not only an individual problem,
it becomes a public health problem.
And we all have to be aware of this.
Sure you heard about something called "jet lag".
Jet lag is what happens when you fly.
You go across time zones, you get to your destination.
For the world it's a time, for you it's another.
And you're a zombie for a few days until you adjust to that new time.
If you travel for pleasure is not serious,
but if you travel for work, it can get tricky.
The things is that you can experience jet lag without leaving home.
Then the social schedule differs from the schedule you have here,
you get what is called "social jet lag".
And we all have social jet lag: we all wake up with an alarm.
Therefore, we are not waking up
at the time our biological clock says.
What's more, it could happen a much more serious social jet lag.
Imagine flying from here to Africa and stay for a week.
From Africa you fly to Asia and stay for a week.
And from here --
Oops this one is in the middle of the Pacific --
you fly to Easter Island and stay for a week and come back.
Pretty crazy a thing to do that, right?
That's what workers do when they are on rotating shifts.
One week they work by day, another in the afternoon,
another at night.
As if they were constantly flying around the world.
And obviously they get ill with those things we said before:
metabolic disorders, cardiovascular disorders.
In addition, WHO, the World Health Organization
listed work on rotating shifts as a risk factor for cancer.
So to sleep poorly or at the wrong time,
is no joke and we have to pay attention.
We research into this subject in the lab.
We research into when we sleep, how much we sleep
because we need data, we need evidence
to later pour it back into society.
We also study what happen with kids
who have to get up so early for school.
And our secret hope is to delay a little bit
school timetables.
You can imagine every time we say this in school, we are heroes.
We also conduct research
to see what happens with our workers on rotating shifts
to improve their quality of life.
And why do we do all this?
First, because what we do in the lab
we hope it gets to the people one day.
Also, because it is what we dream of.
We dream of a clock that works, adapted to the world,
that doesn't make us sick.
And, like everybody else, we want to fulfill our dreams.
Who doesn't want to fulfill their dreams?
But to fulfill your dreams,
you have to start with something quite obvious:
you have to dream.
And to dream, what must be done?
Sleep.
Thank you.
(Applause)