We already knew that sleep boosts our memory, but a new study found that there’s even more to it: sleep sharpens memories overnight. According to researchers at the British University of Exeter, sleep doubles chances of remembering previously forgotten information. The researchers asked a group of study participants to remember some made-up words. After this, half of them got a good night of sleep, while the other half stayed awake. The sleep-group was much better able to recall the words. Amongst other purposes, this knowledge is useful for everyone studying for a test, or preparing for an important presentation. The decision between studying and preparing during the night or getting enough sleep, should be an easy one.