Rambo Tribble writes: 'A research team of Chinese and American scientists claim to have witnessed the mechanism by which sleep contributes to the formation of memories. Using advanced microscopy, the researchers witnessed synapses being formed in the brain of sleeping mice recently exposed to a learning task (abstract). They compared this to similarly tasked mice, that were subsequently sleep-deprived. The sleeping mice showed a marked increase in the formation of new synapses. As one researcher explained, "We thought sleep helped, but it could have been other causes, and we show it really helps to make connections and that in sleep the brain is not quiet, it is replaying what happened during the day and it seems quite important for making the connections.'''