Accomplished neuroscientist Andrew Huberman shares amazing insight into the working ways of our brain and how we can exploit the tools that are naturally available to us.


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Speaker: Andrew Huberman

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There’s one piece of your brain
that is outside your skull.
In fact, you have two.
The rest of your central nervous system is inside your skull
and spinal cord
except lining the back of your eye
is the neural retina
which is three cell layers thick, meaning it’s about as thick as a credit card
and the neural retina is not attached to the brain,
it is brain.
The cells in the neural retina were deliberately placed,
during development they got pushed out of the skull
and deliberately to sense
light events in the environment.
And not just the shapes
of things and what’s moving around out there,
but fundamentally to tell the rest of the brain and nervous system
when to be alert
and when to be asleep
based on
how much light is in the environment
and the quality of that light.
So, viewing morning sunlight
around the time of sunrise,
as well as evening sunlight around the time of sunset,
not just at rise and sunset,
but near those times, a couple of hours on either side
is fundamental for instructing the brain,
a special collection of neurons right above the roof of the mouth
which then instructs all the cells of the body when to be active.
It’s sort of like if you’re a factory
and you need your digestion to work on a particular schedule
and you need your spleen to work on another schedule.
And it’s morning light and evening light in particular.
And the cells
that do this,
they pay attention, not to blue light,
everyone’s kind of obsessed with blue light as it relates to this stuff,
That’s only half the equation.
It’s the contrast between yellow light and blue light,
so in the morning and at sunset,
yellows are getting brighter,
watch a sunrise sometime or a sunset and blues are getting darker
and that contrast is relayed to the brain,
you don’t perceive it,
even blind people
can transmit this information
into the brain
and it says, “make a cortisol pulse,” early in the day to give you energy
and agitate your body
to go be active and then it times the onset of the melatonin pulse in the evening
which is gonna put you to sleep.
And so, when we think about the brain and the nervous system
being isolated, it is isolated,
but as much as it’s a machine and a collection of cells,
they need to work together and they need to know when to be active.
And so, it’s viewing of morning sunlight in particular
and evening sunlight in particular
that anchors
everything that goes on from the top of your skull to the bottom of your feet,
in terms of this basic thing of when to be alert and when to be asleep.
And screens,
but not just screens and not just blue light,
making their way into the hours of say,
11 PM-4 AM do just the opposite.
There was a paper published in Cell, an excellent journal
showing that bright light activation between 11 PM and 4 AM
sends a signal from the eye to a brain structure called the habenula,
the name doesn’t matter,
but it kicks off a disappointment circuit,
it starts suppressing dopamine
and the habenula
is linked to the pancreas,
the brain-body connection,
and starts dysregulating blood sugar.
I think the fundamental
step that everybody should be taking every day for
many aspects of their health,
mental, physical, digestive, immune, all of that
is to get two to 10 minutes of bright light,
first thing in the morning on waking.
Ideally it’s sunlight.
You can do it through a window.
You probably shouldn’t wear sunglasses while you do it.
Don’t stare at the sun until you burn your retinas out or something
and make it painful, please don’t do that.
But just getting bright light exposure first thing in the morning
the nervous system and the rest of the organs of the body
in such a powerful way
that I feel like
if you do that most days,
if you miss a day no big deal,
but if you do that most days,
you’re setting yourself on the path to do all the other sorts of things correctly
and your
biology will thank you for it.