SKIMPING on sleep does awful things to your brain. Planning, problem-solving, learning, concentration,working memory and alertness all take a hit. IQ scores tumble. "If you have been awake for 21 hours straight, your abilities are equivalent to someone who is legally drunk," says Sean Drummond from the University of California, San Diego.
Luckily, it's reversible - and more. If you let someone who isn't sleep-deprived have an extra hour or two of shut-eye, they perform much better than normal on tasks requiring sustained attention, such as taking an exam
These are not the only benefits of a decent night's sleep. Sleep is when your brain processes new memories, practises and hones new skills - and even solves problems. Say you're trying to master a new video game. Instead of grinding away into the small hours, you would be better off playing for a couple of hours, then going to bed. While you are asleep your brain will reactivate the circuits it was using as you learned the game, rehearse them, and then shunt the new memories into long-term storage. When you wake up, hey presto! You will be a better player. The same applies to other skills such as playing the piano, driving a car and, some researchers claim, memorising facts and figures. Even taking a nap after training can help, says Carlyle Smith of Trent University in Peterborough, Ontario.
There is also some evidence that sleep can help produce moments of problem-solving insight. The famous story about the Russian chemist Dmitri Mendeleev suddenly "getting" the periodic table in a dream after a day spent struggling with the problem is probably true. It seems that sleep somehow allows the brain to juggle new memories to produce flashes of creative insight. So if you want to have a eureka moment, stop racking your brains and get your head down.
