Anyone who has pulled an all-nighter knows that our mental abilities take a hit after a sleepless night. But why? What makes sleep so restorative? The answer may be that shut-eye is a biological trade-off for the ability to learn and remember.

A team of researchers from Johns Hopkins Department of Neuroscience, and a second group from the University of Wisconsin–Madison recently showed that sleep streamlines synapses, the junctions between neurons that control the flow of information between neighboring cells. One study found that synapses, which grow when animals are awake and learning, shrink during sleep, so they are ready in the morning to be exercised again. And another showed that the levels of synaptic proteins, which build during waking hours, drop during sleep, and that if this reset process is prevented, mice cannot form new memories. 

The Kavli Foundation spoke to the scientists who conducted this new research, as well as an expert on the relationship between sleep and memory in humans. READ The Kavli Foundation's INTERVIEW WITH THE AUTHORS, and the original articles published by Diering et al., and De Vivo et al.