The scientists presented 68 different women and 38 men between the ages of 18 and 30 years with pictures that showed different situations. The subjects rated the 60 pictures in total according to their emotional value on a scale of 1 to 9, where 1 meant sad and 9 cheerful, respectively calm and excited. After twelve hours did they get some of the pictures? mixed with new motives? to see again. The subjects should now indicate whether they already knew the images and rate them again.
34 of the participants were shown the pictures in the morning and on the same day in the evening. On average, this group rated the already known pictures more positively than when they were first viewed. The other 82 subjects, however, looked at the pictures in the evening and the following morning, so they slept before they looked at the pictures a second time. On average, they found the familiar pictures as negative as when they were first viewed.
So when we see something disturbing, such as a car crash, and remember or want to take a look at that scene, are we reacting much less emotionally if we stayed awake for a while after the experience, ? concludes Rebecca Spencer. Sleep apparently preserves the emotional intensity of an experience as well as the memory itself.
From an evolutionary point of view, this could make a lot of sense: by leaving scary experiences more present in the memory, similar negative situations could be avoided and, in case of doubt, save survival, the researchers suspect.
"Today, for example, does this aspect have any significance for people suffering from post-traumatic stress disorder or eyewitnesses who have to face their memories in court hearings, " explains Rebecca Spencer. display
The results of the research team support recently published studies by other scientists. "However, we are the first to establish a direct link between the storage of emotions and sleep, " write Spencer and her team.Bengi Baran (University of Massachusetts, Amherst) et al .: Journal of Neuroscience, doi: 10.1523 / JNEUROSCI.2532-11.2012 © science.de? Marion Martin