How sleep affects your emotions

It's not just your imagination -- you're more irritable when you're low on zzzzs. Sleep scientist Matt Walker explains how our nightly slumber affects the emotional centers in our brains, and why we can think of sleep as first aid for our feelings.

So exactly, how does a lack of sleep
impact our emotional brain?

Why does that lack of sleep make us

so emotionally irrational
and hyperreactive?

[Sleeping with Science]

Well, several years ago,
we conducted a brain imaging study.

And we took a group of healthy adults.

And we either gave them
a full night of sleep

or we sleep-deprived them.

And then the next day,
we placed them inside an MRI scanner,

and we looked at how
their emotional brain was reacting.

And we focused on one
structure in particular,

it's called the amygdala.

And the amygdala is one
of the centerpiece regions

for the generation
of strong emotional reactions,

including negative emotional reactions.

Now when we looked at those people
who had had a full night of sleep,

what we saw was a nice,
appropriate moderate degree

of reactivity from the amygdala.

It wasn't as though
there was no response at all,

but it was an appropriate response.

Yet in those people
who were sleep-deprived,

that deep emotional brain center
was in fact, hyperactive.

Indeed, the amygdala
was almost 60 percent more responsive

under conditions of a lack of sleep.

But why was that the case?

And what we went on to discover,

is that there's another
brain region that's involved.

This brain region is called
the prefrontal cortex,

and it sits directly above your eyes.

And you can think
of the prefrontal cortex

almost like the CEO of your brain.

It's very good at making
high-level, executive, top-down

control decisions and reactions.

In fact, it's one of the most
evolved regions of our brain.

And one of the parts
of the brain that it controls

is this deep emotional
center, the amygdala.

Now in those people
who had had a full night of sleep,

there was a nice, strong
communication and connection

between the prefrontal cortex,

regulating that deep
emotional brain center.

But in those people
who were sleep-deprived,

that communication, that connection
between the prefrontal cortex

and that deep amygdala
emotional brain center

had essentially been severed.

And as a consequence,

the amygdala was responding
far more reactively

due to a lack of sleep.

It's almost as though without sleep

we become all emotional accelerator pedal,

and too little regulatory control brake.

And that seems to be the reason
that we become so unbuckled

in terms of our emotional integrity

when we haven't been sleeping well.

So that's the bad that can happen

if I take sleep away from you.

But it turns out

that there's something good that happens

when you get your sleep back.

And sleep, particularly
rapid eye movement sleep,

actually offers a form
of emotional first aid.

Because it's during sleep at night

that we take these difficult
emotional experiences

that we've been having during the day,

and that sleep acts almost
like a nocturnal soothing balm,

taking the sharp edges off
those difficult experiences.

And so perhaps it's not time
that heals all wounds,

it's time during sleep that provides
that form of emotional convalescence.

So that when we come back the next day,

we're able to cope
with those emotional memories.