we live in a time where immensely
powerful technology has been completely
embedded into the fabric of our everyday
lives
and a visceral illustration of
technology’s power is spaceflight where
we literally transplant a human body off
of our planet and into the microgravity
environment in outer space but living in
space for just one month causes really
serious health ramifications from the
dramatic loss of bone density and muscle
mass and blood volume to the
reactivation of latent viruses there’s
really no part of the body that goes
untouched when we put it into an
environment to which we are unfamiliar
we don’t think of gravity as a key part
of our health like diet and exercise but
clearly it is so play a game with me
here imagine that we created clothing
that would allow us to adjust our
relationship with gravity here on earth
we would wear those clothes we would
feel lighter we could run faster and
farther and jump higher and there would
be all sorts of advantages but there
would be consequences too we would now
need to make sure that we were getting
enough gravity in our day so that we
didn’t succumb to the same effects as
these astronauts I’m not here to talk to
you about gravity per se but it does
speak to a fundamental truth the
successful functioning of the human body
depends on a variety of environmental
signals and when those signals change
opposes a release
is risk to our health and I am going to
talk to you about one of these powerful
health signals today the signal of light
and to do this we can look to
contemporary hunter-gatherer populations
now these are people that live without
electricity so they are exposed to light
only in the forms that you see in nature
in the study of some of these
populations it’s been observed they get
their peak light exposure between the
hours of 9:00 and noon at which point
they will seek shade during mid-day to
get out of the intense heat and at night
they’re exposed to light only in the
forms of fire and stars and the moon and
like our relationship with gravity has
been for our entire lives
humans relationship with light had
remained constant for millennia all the
way up until 1879 when Thomas Edison
patented the incandescent light bulb
now incandescent light gives off a warm
tone of light similar to that of sunset
and these bulbs can be dimmed but they
are energy inefficient rightfully
worrying policy makers are about their
contribution to global warming and so in
attempts to be more efficient humans
were introduced to compact fluorescent
lighting and these cannot be dimmed and
they give off a strange signature of
light only certain blues and greens and
oranges are represented in their
spectrum and they flicker causing
headaches and fatigue then in 1992 the
Japanese invented light emitting diodes
or LEDs and these had all sorts of
benefits they are energy efficient they
can be dimmed and they are bright and we
find them not only in lamps but also in
our screens like high-definition
televisions and our smart phones and for
the first time ever from electric light
we could generate full spectrum white
light now when you filter out blue from
full spectrum white light we see the
tone of sunset and fire now all of this
lighting technology has fundamentally
changed the way that humans live we now
spend 90% of our time indoors and
according to a survey by the National
Sleep Foundation nearly all US adults
have a screen in their bedroom and use
those devices within an hour of going to
bed compared to ours ancestors we have
less sunshine we have longer periods of
dark of light within a 24 hour day and
correspondingly less darkness and we get
strange tones of light for a given time
of day for instance you can get a full
spectrum daytime signal right before bed
but does all of this matter to our
health and the answer to that is an
unequivocal yes we know that sunshine
has a powerful effect on the synthesis
of the hormone vitamin B and it is now
estimated that nearly set 75 percent of
the United States and over a billion
people worldwide have low vitamin D
status we also know that sunshine is
important for the synthesis of nitric
oxide which is involved in the
regulation of blood pressure which might
be part of the reason why average blood
pressure levels rise linearly the
farther you get from the equator and why
blood pressure rates tend to be higher
in the winter than they are in summer
months but our brain is affected to
animals that are kept in constant in
light conditions have 30% reduced
capacity of key memory centers in the
brain and this translates to absolutely
terrible performance on memory tests
when those animals are switched back to
natural lighting conditions those memory
deficits are reversed and perhaps most
surprisingly it’s recently been
discovered that our fat tissue contains
light receptors when sunlight is shined
on these receptors it causes the
cells to shrink to store less fat and to
become less inflamed and the authors of
this research speculated but they might
have just stumbled across a mechanism
designed to increase fat storage during
winter months which is particularly
interesting in light of the fact that we
spend all of our time indoors and are
nearly always fully clothed so we see
that sunshine is important for hormones
for blood pressure for brain performance
and for the regulation of fat and I can
assure you this is not an exhaustive
list but it’s not the only way that our
light environment has changed we now get
full spectrum white light after sundown
and it’s having a dramatic effect on our
sleep evening bright white light
associates with a reduction in total
sleep and sleep quality both of which
associate with an increase in daytime
sleepiness and reduced cognitive
capacities the next day and so it’ll now
come as no surprise that children that
have a screen in their bedroom perform
worse in academics at every grade level
tested compared to children who do not
have a screen in their bedroom and
sleeping in darkness is important to
adults that sleep with just a little bit
of light on in their room are far more
likely to experience symptoms of
depression and animals that sleep in dim
light gain 50 percent more weight than
their counterparts who sleep in darkness
even when they eat the same amount of
calories and so as I was learning about
all of this information in my work and
the sites or circadian biology lab at
Stanford and my work to optimize human
health and performance I started to
become obsessed about how I could adjust
my relationship with light so that I
could maximize its benefits and minimize
the negative effects of the wrong type
of light at the wrong time and to do
this I aim to maintain a smart daily
light rhythm day evening and night this
is a color temperature scale color
temperature is measured in the units
Kelvin 1000 Kelvin
is the tone of fire five to seven
thousand Kelvin is full spectrum white
light and after seven thousand Kelvin
the light tone tints blue and so by
choosing the right LEDs or LEDs that can
adjust their tone I was able to create a
internal light environment that was
reflective of what was happening outside
at a given time of day here is my office
at 4,000 kelvins at 8 a.m. 6000 kelvins
at 1 p.m. and back down to 3,000 kelvins
by 7:00 and in my bedroom an hour before
going to sleep the light temperature is
2,000 which is again the tone of fire
but lamps are not the only way that we
are getting electric light and so I’ve
also made adjustments to my screens
either through modifying settings or
installable apps you can have it so that
the blue light is pulled out after
sundown now I haven’t only modified my
bulbs I’ve also modified my behavior
morning light has been shown to increase
the restorative nature of sleep at night
and so my morning motto is get up get
out
overall I aim to spend at least 10
minutes outside before noon and at least
30 minutes outside every day now what is
the first thing that people do when they
step outside put on glasses well I
stopped wearing sunglasses and instead I
started to wear special glasses in the
evening to block out blue light from
random sources like opening the
refrigerator and it has been shown that
wearing blue filter and glasses in the
evening will naturally make people want
to go to bed over an hour earlier than
they usually do now this might seem like
a lot of information to digest but we
can keep it simple seek natural light
rhythms day evening and night get
outside when you can and work to have
your indoor spaces reflect what is
happening outside and this can be as
simple as turning off lights that you’re
not using an evening or dimming them to
something more sophisticated as I’ve
mentioned today
yes we live in a world with immensely
powerful technology and it’s only
getting stronger and more invasive and
more immersive and the more the
technology pushes us to live in a manner
that is disconnected from the origin
environmental conditions from which we
came the more that we need
countervailing technology and strategies
to help us stay human in the digital age
societally we have not fully embraced
the powerful effects that light has on
our health but I can envision a day soon
where human centric natural lighting is
the standard for all of our urban areas
and our homes and the default settings
on all of our devices so that we get
something closer to the natural light
signal that the human body needs to
thrive thank you [Applause]
powerful technology has been completely
embedded into the fabric of our everyday
lives
and a visceral illustration of
technology’s power is spaceflight where
we literally transplant a human body off
of our planet and into the microgravity
environment in outer space but living in
space for just one month causes really
serious health ramifications from the
dramatic loss of bone density and muscle
mass and blood volume to the
reactivation of latent viruses there’s
really no part of the body that goes
untouched when we put it into an
environment to which we are unfamiliar
we don’t think of gravity as a key part
of our health like diet and exercise but
clearly it is so play a game with me
here imagine that we created clothing
that would allow us to adjust our
relationship with gravity here on earth
we would wear those clothes we would
feel lighter we could run faster and
farther and jump higher and there would
be all sorts of advantages but there
would be consequences too we would now
need to make sure that we were getting
enough gravity in our day so that we
didn’t succumb to the same effects as
these astronauts I’m not here to talk to
you about gravity per se but it does
speak to a fundamental truth the
successful functioning of the human body
depends on a variety of environmental
signals and when those signals change
opposes a release
is risk to our health and I am going to
talk to you about one of these powerful
health signals today the signal of light
and to do this we can look to
contemporary hunter-gatherer populations
now these are people that live without
electricity so they are exposed to light
only in the forms that you see in nature
in the study of some of these
populations it’s been observed they get
their peak light exposure between the
hours of 9:00 and noon at which point
they will seek shade during mid-day to
get out of the intense heat and at night
they’re exposed to light only in the
forms of fire and stars and the moon and
like our relationship with gravity has
been for our entire lives
humans relationship with light had
remained constant for millennia all the
way up until 1879 when Thomas Edison
patented the incandescent light bulb
now incandescent light gives off a warm
tone of light similar to that of sunset
and these bulbs can be dimmed but they
are energy inefficient rightfully
worrying policy makers are about their
contribution to global warming and so in
attempts to be more efficient humans
were introduced to compact fluorescent
lighting and these cannot be dimmed and
they give off a strange signature of
light only certain blues and greens and
oranges are represented in their
spectrum and they flicker causing
headaches and fatigue then in 1992 the
Japanese invented light emitting diodes
or LEDs and these had all sorts of
benefits they are energy efficient they
can be dimmed and they are bright and we
find them not only in lamps but also in
our screens like high-definition
televisions and our smart phones and for
the first time ever from electric light
we could generate full spectrum white
light now when you filter out blue from
full spectrum white light we see the
tone of sunset and fire now all of this
lighting technology has fundamentally
changed the way that humans live we now
spend 90% of our time indoors and
according to a survey by the National
Sleep Foundation nearly all US adults
have a screen in their bedroom and use
those devices within an hour of going to
bed compared to ours ancestors we have
less sunshine we have longer periods of
dark of light within a 24 hour day and
correspondingly less darkness and we get
strange tones of light for a given time
of day for instance you can get a full
spectrum daytime signal right before bed
but does all of this matter to our
health and the answer to that is an
unequivocal yes we know that sunshine
has a powerful effect on the synthesis
of the hormone vitamin B and it is now
estimated that nearly set 75 percent of
the United States and over a billion
people worldwide have low vitamin D
status we also know that sunshine is
important for the synthesis of nitric
oxide which is involved in the
regulation of blood pressure which might
be part of the reason why average blood
pressure levels rise linearly the
farther you get from the equator and why
blood pressure rates tend to be higher
in the winter than they are in summer
months but our brain is affected to
animals that are kept in constant in
light conditions have 30% reduced
capacity of key memory centers in the
brain and this translates to absolutely
terrible performance on memory tests
when those animals are switched back to
natural lighting conditions those memory
deficits are reversed and perhaps most
surprisingly it’s recently been
discovered that our fat tissue contains
light receptors when sunlight is shined
on these receptors it causes the
cells to shrink to store less fat and to
become less inflamed and the authors of
this research speculated but they might
have just stumbled across a mechanism
designed to increase fat storage during
winter months which is particularly
interesting in light of the fact that we
spend all of our time indoors and are
nearly always fully clothed so we see
that sunshine is important for hormones
for blood pressure for brain performance
and for the regulation of fat and I can
assure you this is not an exhaustive
list but it’s not the only way that our
light environment has changed we now get
full spectrum white light after sundown
and it’s having a dramatic effect on our
sleep evening bright white light
associates with a reduction in total
sleep and sleep quality both of which
associate with an increase in daytime
sleepiness and reduced cognitive
capacities the next day and so it’ll now
come as no surprise that children that
have a screen in their bedroom perform
worse in academics at every grade level
tested compared to children who do not
have a screen in their bedroom and
sleeping in darkness is important to
adults that sleep with just a little bit
of light on in their room are far more
likely to experience symptoms of
depression and animals that sleep in dim
light gain 50 percent more weight than
their counterparts who sleep in darkness
even when they eat the same amount of
calories and so as I was learning about
all of this information in my work and
the sites or circadian biology lab at
Stanford and my work to optimize human
health and performance I started to
become obsessed about how I could adjust
my relationship with light so that I
could maximize its benefits and minimize
the negative effects of the wrong type
of light at the wrong time and to do
this I aim to maintain a smart daily
light rhythm day evening and night this
is a color temperature scale color
temperature is measured in the units
Kelvin 1000 Kelvin
is the tone of fire five to seven
thousand Kelvin is full spectrum white
light and after seven thousand Kelvin
the light tone tints blue and so by
choosing the right LEDs or LEDs that can
adjust their tone I was able to create a
internal light environment that was
reflective of what was happening outside
at a given time of day here is my office
at 4,000 kelvins at 8 a.m. 6000 kelvins
at 1 p.m. and back down to 3,000 kelvins
by 7:00 and in my bedroom an hour before
going to sleep the light temperature is
2,000 which is again the tone of fire
but lamps are not the only way that we
are getting electric light and so I’ve
also made adjustments to my screens
either through modifying settings or
installable apps you can have it so that
the blue light is pulled out after
sundown now I haven’t only modified my
bulbs I’ve also modified my behavior
morning light has been shown to increase
the restorative nature of sleep at night
and so my morning motto is get up get
out
overall I aim to spend at least 10
minutes outside before noon and at least
30 minutes outside every day now what is
the first thing that people do when they
step outside put on glasses well I
stopped wearing sunglasses and instead I
started to wear special glasses in the
evening to block out blue light from
random sources like opening the
refrigerator and it has been shown that
wearing blue filter and glasses in the
evening will naturally make people want
to go to bed over an hour earlier than
they usually do now this might seem like
a lot of information to digest but we
can keep it simple seek natural light
rhythms day evening and night get
outside when you can and work to have
your indoor spaces reflect what is
happening outside and this can be as
simple as turning off lights that you’re
not using an evening or dimming them to
something more sophisticated as I’ve
mentioned today
yes we live in a world with immensely
powerful technology and it’s only
getting stronger and more invasive and
more immersive and the more the
technology pushes us to live in a manner
that is disconnected from the origin
environmental conditions from which we
came the more that we need
countervailing technology and strategies
to help us stay human in the digital age
societally we have not fully embraced
the powerful effects that light has on
our health but I can envision a day soon
where human centric natural lighting is
the standard for all of our urban areas
and our homes and the default settings
on all of our devices so that we get
something closer to the natural light
signal that the human body needs to
thrive thank you [Applause]
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