Memories are stored in your brain while you sleep
This is how the brain forms memories during sleep - neuroscience news

Neuroscientists have for the first time recorded the brain activity underlying memory. They did this in epileptic patients that had electrodes implanted for surgery (this is normal procedure in these patients). The participants were shown a set of pictures to memorize, and then took an afternoon nap. Recordings through the electrodes revealed a characteristic electrical band pattern (known as gamma oscillations), that occurred in two phases: a superficial processing phase that took place during the first half a second after image presentation, and a deep processing phase after that. For memory to form, this activity during the deep processing phase had to coincide with a particular form of activity in the hippocampus, known as ripples. When gamma activity was reactivated when the hippocampal ripples did not occur, the information about the picture was forgotten.

Read the full story: Ruhr Univerität Bochum
Scientific publication: Nature Communications