The brain can significantly overreact to negative experiences when there is a lack of sleep, according to a new study.

Researchers at Harvard Medical School and the University of California, Berkeley, found that sleep-deprived people suffer from a shutdown of the prefrontal lobe, a region of the brain which usually keeps emotions under control.

The new study tracked 26 healthy people who were either sleep-deprived and stayed awake for 35 hours and another group of people who had a normal sleep pattern. The volunteers’ brains were scanned by functional magnetic resonance imaging (MRI) which monitored their brain activity based on blood flow, while they viewed 100 images. In the beginning, the images were reproted as emotionally neutral but became increasingly aversive over some time for those who were deprived of sleep.

The study, according to researchers, may offer some insight into the connection between sleep deprivation and psychiatric disorders since sleep deprivation has been known to cause a breakdown of the immune system as well as metabolism and brain processes like learning and the memory. However, the link between sleep and the brain’s mental balance has not be studied extensively.

“This adds to the critical list of sleep’s benefits,” said Matthew Walker, a researcher from the University of California, Berkeley. “Sleep appears to restore our emotional brain circuits, and in doing so prepares us for the next day’s challenges and social interactions. Most importantly, this study demonstrates the dangers of not sleeping enough. Sleep deprivation fractures the brain mechanisms that regulate key aspects of our mental health. The bottom line is that sleep is not a luxury that we can optionally choose to take whenever we like. It is a biological necessity, and without it, there is only so far the band will stretch before it snaps, with both cognitive and emotional consequences.”