1: How many times have we heard or said those unfortunate words? It might be the unfolding tragedy when “a soldier irrationally responds to a provocative civilian, a physician to an entitled patient, or a parent to a misbehaving child,” writes Matthew Walker in Why We Sleep: Unlocking the Power of Sleep and Dreams.

All too often, regret is the emotion that follows.

And many times, it is tired, sleep-deprived people who act out this anger and hostility. We instinctively understand “inadequate sleep plays havoc with our emotions,” Matthew writes. All parents likely remember holding a screaming child and saying, “Well, ________ just didn’t get enough sleep last night.”

Turns out this parental intuition is now backed by science.

In one research study at his laboratory at the University of California, Berkeley, Matthew and his team monitored two groups: one who stayed awake all night and one who slept normally. The following day both groups were shown the same one hundred photos while being hooked up to a brain scanner. The photographs “ranged from neutral in emotional content (e.g., a basket, a piece of driftwood) to emotionally negative (e.g., a burning house, a venomous snake about to strike).”

Matthew then compared the increase in brain response to the progressively negative emotional triggers. “Analysis of the brain scans revealed the largest effects I have measured in my research to date,” he writes.

2: What’s happening here? The amygdala part of our brains is a “key hot spot for triggering strong emotions such as anger and rage, and linked to the fight-or-flight response.” For the sleep-deprived group, there was a more than 60 percent amplification in emotional reactivity.

“In contrast, the brain scans of those individuals who were given a full night’s sleep evinced a controlled, modest degree of reactivity in the amygdala, despite viewing the very same images,” Matthew writes. “It was as though, without sleep, our brain reverts to a primitive pattern of uncontrolled reactivity. We produce unmetered, inappropriate emotional reactions, and are unable to place events into a broader or considered context.”

When we are sleep deprived, we lose our ability to “rein in our atavistic impulses—too much emotional gas pedal (amygdala) and not enough regulatory brake (prefrontal cortex),” Matthew observes. “Without the rational control given to us each night by sleep, we’re not on a neurological -and hence emotional – even keel.”

Interestingly, insufficient sleep does not push our brains into a negative mood state and hold it there. “Rather, the under-slept brain swings excessively to both extremes of emotional valence, positive and negative,” notes Matthew. “In a flash, sleep-deprived subjects would go from being irritable and antsy to punch-drunk giddy, only to then swing right back to a state vicious negativity.”

Lack of sleep and resulting aggression have been linked to children’s bullying and behavioral problems. Additionally, “studies of adolescents have identified a link between sleep disruption and suicidal thoughts, suicide attempts, and, tragically, suicide completion in the days after,” Matthew writes.

A link between sleep deprivation and violence has also been documented in adult prison populations; places which “are woefully poor at enabling good sleep that could reduce aggression, violence, psychiatric disturbance, and suicide,” Matthew notes, “which, beyond the humanitarian concern, increases costs to the taxpayer.”

3: Problematic issues also arise from extreme swings toward positive moods. “Hypersensitivity to pleasurable experiences can lead to sensation-seeking, risk-taking, and addiction,” writes Matthew. “Sleep disturbance is a recognized hallmark associated with addictive substance use. Insufficient sleep also determines relapse rates in numerous addiction disorders, associated with reward cravings that are unmetered, lacking control from the rational head office of the brain’s prefrontal cortex.”

Fortunately, the opposite is also true.

“By improving sleep quantity, quality, and regularity, [Dr. Allison] Harvey and her team have systematically demonstrated the healing abilities of sleep for the minds of numerous psychiatric populations,” notes Matthew. “She has intervened with the therapeutic tool of sleep in conditions as diverse as depression, bipolar disorder, anxiety, and suicide, all to great effect.

“By regularizing and enhancing sleep, Dr. Harvey has stepped these patients back from the edge of crippling mental illness,” Matthew writes.

More tomorrow.


Reflection: Am I getting enough sleep regularly? If not, what am I going to do about it?

Action: Journal about my answers to the questions above.

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