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

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Why does that lack of sleep make us

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so emotionally irrational[br]and hyperreactive?

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[Sleeping with Science]

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

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And we took a group of healthy adults.

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And we either gave them[br]a full night of sleep

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or we sleep-deprived them.

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

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and we looked at how[br]their emotional brain was reacting.

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And we focused on one[br]structure in particular,

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it's called the amygdala.

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And the amygdala is one[br]of the centerpiece regions

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for the generation[br]of strong emotional reactions,

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including negative emotional reactions.

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

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what we saw was a nice,[br]appropriate moderate degree

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of reactivity from the amygdala.

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

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but it was an appropriate response.

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Yet in those people[br]who were sleep-deprived,

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that deep emotional brain center[br]was in fact, hyperactive.

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Indeed, the amygdala[br]was almost 60 percent more responsive

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under conditions of a lack of sleep.

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But why was that the case?

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And what we went on to discover,

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is that there's another[br]brain region that's involved.

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This brain region is called[br]the prefrontal cortex,

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and it sits directly above your eyes.

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And you can think[br]of the prefrontal cortex

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almost like the CEO of your brain.

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

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control decisions and reactions.

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

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And one of the parts[br]of the brain that it controls

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is this deep emotional[br]center, the amygdala.

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

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there was a nice, strong[br]communication and connection

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between the prefrontal cortex,

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regulating that deep[br]emotional brain center.

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But in those people[br]who were sleep-deprived,

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that communication, that connection[br]between the prefrontal cortex

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and that deep amygdala[br]emotional brain center

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had essentially been severed.

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And as a consequence,

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the amygdala was responding[br]far more reactively

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due to a lack of sleep.

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It's almost as though without sleep

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we become all emotional accelerator pedal,

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and too little regulatory control brake.

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And that seems to be the reason[br]that we become so unbuckled

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in terms of our emotional integrity

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when we haven't been sleeping well.

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So that's the bad that can happen

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if I take sleep away from you.

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But it turns out

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that there's something good that happens

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when you get your sleep back.

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And sleep, particularly[br]rapid eye movement sleep,

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actually offers a form[br]of emotional first aid.

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Because it's during sleep at night

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that we take these difficult[br]emotional experiences

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that we've been having during the day,

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and that sleep acts almost[br]like a nocturnal soothing balm,

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taking the sharp edges off[br]those difficult experiences.

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

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

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So that when we come back the next day,

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we're able to cope[br]with those emotional memories.