Without sleep, the emotional centers of our brains dramatically overreact to bad experiences, research now reveals.
“When we’re sleep deprived, it’s really as if the brain is reverting to more primitive behavior, regressing in terms of the control humans normally have over their emotions,” researcher Matthew Walker, a neuroscientist at the University of California, Berkeley, told LiveScience.
Anyone who has ever gone without a good night’s sleep is aware that doing so can make a person emotionally irrational. While past studies have revealed that sleep loss can impair the immune system and brain processes such as learning and memory, there has been surprisingly little research into why sleep deprivation affects emotions, Walker said.
Walker and his colleagues had 26 healthy volunteers either get normal sleep or get sleep deprived, making them stay awake for roughly 35 hours. On the following day, the researchers scanned brain activity in volunteers using functional magnetic resonance imaging (fMRI) while they viewed 100 images. These started off as emotionally neutral, such as photos of spoons or baskets, but they became increasingly negative in tone over time—for instance, pictures of attacking sharks or vipers.