Transcriber: Leonardo Silva Reviewer: Reiko Bovee
I'd just like a little bit of a show of hands here
to find out how many people here
feel that they've gotten an adequate amount of sleep over the past month.
(Laughter)
Do I see any hands? A couple of hands.
Well, like most Americans,
the people here are simply not getting enough sleep.
I'd like to ask one other question.
How many people have never driven a car when you were drowsy?
Two people, OK.
Yeah. Well, that's reflective of all of our lives these days.
The question that I'm going to pose is:
Why are we not sleeping as much?
Ten times as many people today
are sleeping less than six hours a night
than, for example, when I was growing up.
If we look at kids of all ages,
five-year-olds are getting two hours of sleep less at night
than they did in earlier times.
Ten-year-olds, fifteen-year-olds, twenty-year-olds,
we're all sleeping a couple of hours less per night
than we did in the past.
So, the question is: Why are we sleeping less?
And I think one of the key issues
is actually the light to which we are exposed, artificial light.
And that may seem surprising,
but electricity and the ability to turn it on whenever we wish,
along with caffeine and other aspects of our technological lives,
are actually reducing the amount of sleep that we have.
And paradoxically, in order to understand this,
we have to understand how sleep is organized
within the usual day.
And we have two major regulatory processes
that affect how alert we are at any given moment.
One of them is related to how many hours that we've slept
and how long we've been awake,
and the second is an internal clock in the brain
that times sleep and times our tendency to feel alert
and our tendency to feel sleepy.
And paradoxically, that internal clock in the brain
sends out a stronger and stronger drive
for waking as the day wears on
and it opposes what would, otherwise,
be an increasing drive for sleep,
the longer that we're awake.
And this reaches a real apex
near the end of our waking day,
and we just have this internal clock sending out
this strong "ahhh" signal to keep us awake,
and that's when we get this second wind
near the evening part of our day.
What turns off this orchestrated increasing energy and alertness
is the release of the sleep-promoting hormone, melatonin.
And that hormone is typically released an hour or two
before we go to bed at night.
But that release of the hormone
can be suppressed by light
and it can also be shifted by light.
So light exposure in the evening
can not only suppress the release of that hormone today,
but make it occur later on subsequent days.
And I first learned what a profound effect this was having
when we made the discovery, a few years ago,
that some blind people, who have no conscious light perception --
that their internal circadian clock
can be shifted by light that they can't see.
And that's because just in the same way
that the ear has two functions --
one is for hearing and the other is for balance --
also the eye has two functions:
one is for seeing each other
and the other is for circadian photoreception
or resetting this internal clock.
And so, in this individual,
even with his eyes covered --
he has no ability to sense the light
and also no response, hormonally,
to his being exposed to light.
But when his eyes are exposed,
even though he is completely blind and unable to see the light,
it immediately suppresses the release
of the sleep-promoting hormone, melatonin.
But the amazing thing was,
when he lived with sighted people,
we realized that the timing of this hormone
was beginning to be released --
the secretion of this hormone was being released
at 11 or 12 o'clock at night.
Whereas when he became an upperclassman
at Boston College and got his own room,
suddenly you notice that he was beginning to release this hormone
in the afternoon,
and it was actually reaching its peak
at midnight.
And it made me reflect on the fact
that midnight is called midnight
because it's actually the middle of the night,
if you were to look at the timing of the Sun rising and setting.
But, of course, many people today
are just beginning to check their e-mail at midnight,
start their homework, begin writing that novel
and taking on all sets of other challenges
and not even beginning to think about going to sleep.
And so I actually went to an area,
where there's not electricity.
It's about five hours outside of Curitiba, Brazil,
where I managed to find a home,
where there were no electric lights.
And I went to visit the parents of that family,
and there were seven children.
One of the things I was curious about
was, you know, how they managed
when it got dark, at six o'clock in the evening.
The mother then said, "Well, typically we go to bed."
So, I said, "What do you do if a child wakes up?"
Because they're in this one room,
with a dirt floor,
and all nine of them are sleeping in this room.
And I'm thinking, you know, "If we had to sleep with our kids,
what a chaos, pandemonium..."
And so I said, "What do you do
when it's dark and the kids wake up during the night?"
And the translator, back and forth, Dr. Louzada,
asking over and over again my question in different ways.
And finally, the woman understood the question and she said,
"We never wake up during the night.
The children... You know, we go to bed at dusk,
and the children wake up at dawn."
And I realized that the artificial light to which we're exposed
is wreaking havoc on our ability to remain in synch
with the 24-hour day.
And I began to, then, look at the results of our laboratory experiments.
We had studied hundreds of people
in which we defined the daily rhythm of light sensitivity.
And here, you can see that light exposure in the evening hours,
resets our internal clock to a later hour,
and light exposure in the morning is resetting your circadian system
to an earlier hour,
and that's how we keep in synch with the 24-hour day.
As I mentioned, this second wind
is lined up to occur late in the evening,
to allow us to stay awake for this marathon
of 16-hour wakefulness that we all
experience each day.
And then, I was thinking about what must it have looked like
200 years ago?
Or what would it have looked like in this blind individual,
who was living in his own room and didn't have electric light?
We would expect the daily rhythm of light sensitivity
to take this shape, then melatonin would be released
as it was in his case, at about five o'clock in the afternoon.
So, the second wind would actually be taking place
when we were all running to get a coffee break and so on.
The artificial light to which we're ordinarily exposed
has pushed the circadian system to a later hour
and shifted us to the equivalent of Hawaiian time,
shifted our brains westward,
placed this second wind late in the evening
and squeezed the timing available for our biological night,
because we're still getting up with the chickens.
In fact, the biggest segment of the working population,
in terms of its temporal distribution,
is for jobs starting between 3:30 and 6:30 in the morning.
So, the jobs and the work are starting earlier,
our kids are going to school earlier --
we're making the high school kids start at sevensomething in the morning,
even though 100 years ago they didn't start till nine.
Kids, back then, didn't even use alarm clocks
to get up for school.
How many of you never used an alarm clock
to get up when you were going to school,
like 95% of the kids did at that time?
So, we've created this big squeeze.
So we have this early wake time,
this circadian surge in wake propensity
and it's an unintended consequence of artificial light.
And then, when we add in caffeine,
many people don't realize that it has half-life of 6 to 9 hours.
So, when we take it after dinner,
it's going to interfere with the restorative value of sleep
that we would otherwise get.
The function of sleep is to repair and reorganize the brain.
Sleep is critical for learning.
In fact, we integrate the knowledge that we've learned today
with our prior experiences
and we rehearse places we've been
and routes that we've taken and so on.
During the night, when we are asleep,
it is also the time that we get insight.
Now, if we don't get enough sleep --
we're one of the few animals
that deprives ourselves of sleep,
and most other species,
the only time that they're sleep deprived
is when they're not getting enough to eat.
And so, the two systems are intertwined.
So, we want to eat more if we're not sleeping enough.
If we go on a diet and try to restrict our calories,
but we're also restricting our sleep,
then 75% of the weight that we lose
will be in body mass rather than from fat,
because of the changes in the hormonal environment
that occur when we're not getting enough sleep.
If you sleep for four, five hours a night,
even for a week,
men's testosterone levels drop to the same degree
that they would having aged ten years.
So, it has many different effects.
It increases distractibility,
kids become hyperactive.
Paradoxically, they don't become sleepy,
but they have difficulty focusing attention.
And we all become a little bit hypomanic.
We don't quite become manic,
but we get this feeling of euphoria
and that may be why sleep loss
is associated with burnout, depression
and other adverse mental health consequences.
And we're sleep depriving our kids.
You know, they're spending 8.5 hours a day on recreational media,
if they have a TV in their bedroom.
And it turns out that they're spending
more time doing that than sleeping.
So, it's no wonder that they're hyperactive.
One out of ten twelve-year-old boys
is now diagnosed with ADHD.
So, what to do?
To thrive, you have to decide if sleep is a priority.
Establish a regular bedtime.
Establish a regular wake time.
Find a cool, dark, quiet place to sleep
and make your bedroom a technology-free zone,
because it's going to interfere with your ability to sleep.
Get rid of the caffeine,
get rid of the alarm clock
and find out how much sleep you really need
and then try to get that.
And what could be the benefits?
First of all, you're going to be able to concentrate,
so that you can perform better,
you can be more accurate.
You'll have greater insight,
you'll have faster reflexes,
reduced risk of injury,
you'll optimize your metabolic fitness
and your appetite, enhance your immunity,
decrease your risk of infection,
reduce your risk of diseases like diabetes,
and stroke, and cancer and heart disease.
Ben Franklin, famously,
in the Poor Richard's Almanack, said,
"There will be sleeping enough in the grave."
One thing I can tell is that you'll get to that grave sooner...
(Laughter) ...if you don't sleep enough.
If you want to thrive well alive,
sleep.
Thank you.
(Applause)