The brain benefits of deep sleep -- and how to get more of it

What if you could make
your sleep more efficient?

As a sleep scientist,

this is the question
that has captivated me

for the past 10 years.

Because while the lightbulb
and technology have brought about a world

of 24-hour work and productivity,

it has come at the cost

of our naturally occurring
circadian rhythm

and our body's need for sleep.

The circadian rhythm dictates
our energy level throughout the day,

and only recently we've been conducting
a global experiment on this rhythm,

which is putting our sleep health

and ultimately
our life quality in jeopardy.

Because of this,

we aren't getting the sleep we need,

with the average American
sleeping a whole hour less

than they did in the 1940s.

For some reason,

we decided to wear it as a badge of honor

that we can get by on not enough sleep.

This all adds up to a real health crisis.

Most of us know that poor sleep
is linked to diseases

like Alzheimer's, cardiovascular disease,

stroke and diabetes.

And if you go untreated
with a sleep disorder like sleep apnea,

you're more likely
to get many of these illnesses.

But did you know about sleep's impact
on your mental states?

Poor sleep makes us
make risky, rash decisions

and is a drain
on our capacity for empathy.

When sleep deprivation literally makes us
more sensitive to our own pain,

it's not so surprising that we have
a hard time relating to others

and just generally
being a good and healthy person

when we're sleep-deprived.

Scientists are now starting to understand

how not only the quantity

but also the quality of sleep
impacts our health and well-being.

My research focuses

on what many scientists believe
is the most regenerative stage of sleep:

deep sleep.

We now know that generally speaking,

there are three stages of sleep:

light sleep,

rapid eye movement or REM

and deep sleep.

We measure these stages by connecting
electrodes to the scalp, chin and chest.

In light sleep and REM,

our brain waves are very similar
to our brain waves in waking life.

But our brain waves in deep sleep
have these long-burst brain waves

that are very different
from our waking life brain waves.

These long-burst brain waves
are called delta waves.

When we don't get the deep sleep we need,

it inhibits our ability to learn

and for our cells and bodies to recover.

Deep sleep is how we convert
all those interactions

that we make during the day

into our long-term memory
and personalities.

As we get older,

we're more likely to lose
these regenerative delta waves.

So in way, deep sleep and delta waves

are actually a marker
for biological youth.

So naturally, I wanted to get
more deep sleep for myself

and I literally tried almost every gadget,
gizmo, device and hack out there --

consumer-grade, clinical-grade,

what have you.

I learned a lot and I found
I really do need, like most people,

eight hours of sleep.

I even shifted my circadian component

by changing my meals,
exercise and light exposure,

but I still couldn't find a way
to get a deeper night of sleep ...

that is until I met
Dr. Dmitry Gerashchenko

from Harvard Medical School.

Dmitry told me about
a new finding in the literature,

where a lab out of Germany showed
that if you could play certain sounds

at the right time in people's sleep,

you could actually make sleep
deeper and more efficient.

And what's more, is that this lab showed

that you actually could improve
next-day memory performance

with this sound.

Dmitry and I teamed up,

and we began working on a way
to build this technology.

With our research lab
collaborators at Penn State,

we designed experiments
in order to validate our system.

And we've since received grant funding
from the National Science Foundation

and the National Institute of Health

to develop this deep-sleep
stimulating technology.

Here's how it works.

People came into the lab

and we hooked them up
to a number of devices,

two of which I have on right here --

not a fashion statement.

(Laughter)

When we detected
that people were in deep sleep,

we played the deep-sleep
stimulating sounds

that were shown
to make them have deeper sleep.

I'm going to demo this sound
for you right now.

(Waves crash)

Pretty weird, right?

(Laughter)

So that sound is actually at the same
burst frequency as your brain waves

when your brain is in deep sleep.

That sound pattern
actually primes your mind

to have more of these
regenerative delta waves.

When we asked participants
the next day about the sounds,

they were completely unaware
that we played the sounds,

yet their brains responded
with more of these delta waves.

Here's an image of someone's brain waves
from the study that we conducted.

See the bottom panel?

This shows the sound being played
at that burst frequency.

Now look at the brain waves
in the upper part of the graph.

You can see from the graph

that the sound is actually producing
more of these regenerative delta waves.

We learned that we could
accurately track sleep

without hooking people up to electrodes,

and make people sleep deeper.

We're continuing to develop

the right sound environment
and sleep habitat

to improve people's sleep health.

Our sleep isn't
as regenerative as it could be,

but maybe one day soon,

we could wear a small device

and get more out of our sleep.

Thank you.

(Applause)