A good night’s sleep may make bad memories worse

22 January 2012
Posted by Hannah Critchlow.

A study published this week in the Journal of Neuroscience indicates that sleep can reinforce unpleasant memories. Remaining awake, on the other hand, helps you to forget.

University of Massachusetts, Amherst scientist Rebecca Spencer and her colleagues showed groups of volunteers a series of images and asked them to rate how emotionally harrowing they were.

12 hours later, after one group had been allowed to sleep for 8 hours, whilst the other group were forced to stay awake, the volunteers were then asked to reexamine the pictures.

Those who slept were much better at remembering which images they had already seen compared with those who stayed awake. 

Not only that, but those who slept still rated the images to be as, if not more, traumatic as the first time they saw them. Those who stayed awake, on the other hand, found the images to be less harrowing after 12 hours.

The researchers controlled for the fact that the sleep deprived group were not simply too tired to respond to the pictures emotionally by repeating the experiment at different times of day.

These results may explain why some people can find it difficult to fall asleep after a traumatic experience, because this is the brains way of stopping you remembering something that would be better off forgotten.

So, contrary to the prevailing view that 'all will seem better after a good night's sleep' - this might actually be the opposite of 'what the doctor ordered' for people exposed to traumatic events. 

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