Why is sleep so important for learning and memory? Neuroscientists from the Csicsvari group at the Institute of Science and Technology Austria (ISTA) provided new insight into this essential function by monitoring neuronal activity in rat brains for up to 20 hours of sleep following spatial learning. Central to the findings are reorganizations of neuronal activity patterns during sleep to reflect those seen during memory recollection upon awakening. The findings were published in Neuron.