You’ve probably heard the old saying: Never go to bed angry: or the hard feelings will fester and resentment will build.
Now the adage the adage has been put to the test. And in a recent study in The Journal of Neuroscience, scientists found there is some truth to it: Going to sleep after experiencing negative emotions appears to reinforce or “preserve” them.
Scientists recruited 106 men and women and exposed them to images that elicited various emotions. In some cases the emotions were negative — for instance, after seeing an unsettling image of an accident or traumatic scene. In other cases, the images produced positive or neutral emotions.
The researchers then looked at what happened when the subjects saw them again 12 hours later — either in the morning after a night of sleep, or at the end of a full day of wakefulness. They found that staying awake blunted the emotional response to seeing the upsetting images again. But when the subjects were shown the disturbing images after a night of sleep, their response was just as strong as when they had first seen them — suggesting that sleep “protected” the emotional response.
Other studies have found that sleep, perhaps as an evolutionary mechanism, enhances emotional memories. Many people have trouble sleeping after an unsettling experience, and that might be the brain’s way of trying to keep the memory or emotions from being stored.
Bottom line: the research suggests that going to sleep upset or disturbed preserves the emotion.