Most of us know that sleepless nights can unhinge your emotions. Now scientists have a better idea of why this happens. They’ve shown that lack of sleep strongly activates the brain’s emotional centers and weakens the brain circuits that keep your emotions under control.
Scientists know that lack of sleep can interfere with your health in many ways. It can disrupt your learning and memory and your ability to fight disease. But they’ve understood much less about how sleep and emotions are connected in the brain.
NIH-funded researchers scanned the brains of 26 healthy adults while they looked at 100 images. At first, the images were neutral—like a chair or a bowl of fruit. Later, they became more unpleasant and disturbing—like a dirty toilet bowl, a burn victim or mutilated bodies.
Some participants had a good night’s sleep before the brain scan. Others had been kept awake for about 35 hours straight—about how long you’d be up if you stayed awake all night and into the next afternoon without naps.
For everyone, the disturbing pictures led to greater activation of a primitive brain region that triggers strong emotions. But the activation was 60% more intense in the people who were sleep deprived and spread over a larger area.
Lack of sleep had another effect on the brain’s circuitry. In the sleep-deprived group, the brain’s emotion center seemed to be more strongly connected to a primitive, impulsive brain region and less connected to a region that normally keeps emotions and behaviors in check.
The researchers say their study demonstrates the dangers of not sleeping enough. Their findings suggest that sleep restores the control of our emotional brain circuits and helps us face the next day’s challenges and social interactions.