When the brain is triggered to recall a memory during sleep, memories are made stronger.
By associating odor with memories, researchers show that sleep helps keep memories strong.
The finding could be applied to help people address traumatic memories.
A new study claims the best way to remember something important is to remember it while you are asleep.
The research in this week's Nature Neuroscience, claims reactivating newly learned memories during sleep rather than when awake does a better job of strengthening the memory trace.
The work, led by Björn Rasch of the University of Basel in Switzerland could have clinical implications for treating disorders such as post traumatic stress disorder (PTSD).
The research involved training subjects in a spatial memory task to learn an object's location in a grid. At the same time an odor was released -- the idea being to associate the memory with the smell.
One group then went to sleep, while the second group stayed awake.
After about 20 minutes, while the sleeping group's brain wave patterns were in slow wave sleep (SWS), both groups were subjected to the same odor again to reactivate the memory. Another 20 minutes later, the sleeping group were woken, and both groups were given a similar task, but the objects were in different locations and without the odor.