Is your sleeping brain more interested in negative memories?

There’s a scientific reason why you may cling to negative memories in favor of other everyday experiences: According to new research study, those are the ones your brain prefers while you sleep. And even though it’s no fun remembering uncomfortable or hurtful moments, a possible explanation as to why your resting mind prefers the darker vignettes is to straight-up protect you.

Thrive Global reports that at the Society for Neuroscience’s annual conference, results were presented from a study in which 57 volunteers reviewed photos that were either neutral (shown on the right side of a screen) or negative (shown on the left). During a memory test, researchers found those who stayed awake couldn’t remember which side of the screen any of the images were displayed, but those who took the test after sleeping in the lab overnight remembered the negative ones in particular.

According to the researchers, as an evolutionary defense, your brain might remember negative stimuli in particular to prevent you from getting hurt in the future.

So what’s the deal with those who got some shut-eye remembering the bad stuff? According to the researchers, it might have to do with evolution: Your brain remembers negative stimuli to prevent you from getting hurt in the future.

“You discover some nice-looking berries and eat them, but then it turns out they’re quite poisonous and you get really sick. In that case, remembering what these berries look like and where you found them could actually help you not to make the same mistake again,” lead researcher Roy Cox, PhD, told Thrive Global. “That could be a clear advantage that becomes selected by evolutionary processes.”

The study researchers aren’t exactly sure how sleep makes you remember negative memories better, but they’re investigating that big question mark next. In the meantime, catch some zzz’s—and just know your brain is trying to do best by you, even if you wake up spooked or sad every now and then.

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