When You Lose Sleep, Your Brain Can't Read Other People's Emotions

After 24 hours without sleep, the brain begins to overestimate threat.

When You Lose Sleep, Your Brain Can't Read Other People's Emotions

Sleep is the foundation of our day, and when we don't get enough of it, strange things start happening to our minds and bodies. A new study has found that when we go long enough without sleep, we lose our ability to read facial expressions.


Most Americans don't get enough sleep, trading in those hours of blissful rest so they can work and get to work. Researchers Matthew Walker, a professor of psychology and neuroscience at UC Berkeley, echoed these concerns in a press release, stating that this lack of sleep affects “over two-thirds of people in the developed nations.”

“Recognizing the emotional expressions of someone else changes everything about whether or not you decide to interact with them, and in return, whether they interact with you."

The experiment was comprised of 18 healthy adults. After receiving a full night's sleep, researchers had them all view 70 different facial expressions ranging from friendly to threatening. Then the researchers had the participants stay awake for 24 hours. The researchers then put the participants through the same test and took measurements of their heart rates and scanned their brains.

The results showed the participants' sleep-deprived brains couldn't distinguish one facial expression from another. MRIs revealed the anterior insula and anterior cingulate cortex — regions of the brain responsible for emotion — had gone dark. The participants tended to perceive most of the expressions they saw as threatening, even the friendly and neutral ones.

Walker added:

“Insufficient sleep removes the rose tint to our emotional world, causing an overestimation of threat. This may explain why people who report getting too little sleep are less social and more lonely."

If your friends indicate that you've been a real grouch lately, maybe consider catching a full night's sleep. In her Big Think interview, Arianna Huffington discusses the importance of having a well-rested body and mind:

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