How many times, when troubled, we’ve heard the phrase “tomorrow will be another day”? The new day might not bring the solution for every kind of problem but, in fact, will enable us to reflect on things in a calm and rational fashion. This is stated in a recent study by Matthew Walker, a neuroscientist at the University of California, Berkeley.
What Walker and his team tried to measure is how sleeping can help us to process bad experiences. To do so, they chose a group of 34 healthy young persons who were divided in two groups. The subjects were exposed to a different range of pictures, from bland objects – such as a kettle on a counter top – to shocking images, at 12-hour intervals.
One of the groups watched the images during the day, without sleeping in between, while the other group watched them before a full night sleep and then the morning after. They were requested to rate their reactions and at the same time a MRI scanner measured their brain activity.
The results show that during the REM sleep the part of the brain that processes the emotions (the amygdala) decreased its activity, so that the prefrontal cortex, linked to rational actions, probably weakened the impact of a bad experience. Also, they noticed a drop in the levels of brain chemicals that are linked to stress.
“Somewhere between the initial event and the later point of recollecting, the brain has performed an elegant trick of divorcing emotions from memory, so it’s no longer itself emotional,” Walker said.
The findings note that an “overnight therapy” may be successful against painful memories and underline that we shouldn’t underestimate a good night sleep.
van der Helm E, Yao J, Dutt S, Rao V, Saletin JM, & Walker MP (2011). REM Sleep Depotentiates Amygdala Activity to Previous Emotional Experiences. Current biology : CB PMID: 22119526