Problem-solving or sound asleep?
Skimping on sleep does awful things to your brain.

"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. Skimping on sleep does awful things to your brain. Planning, problem-solving, learning, concentration, working memory and alertness all show a decline in performance.

Conversely, 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. "Attention is the base of a mental pyramid," says Drummond. "If you boost that, you can't help boosting everything above it". Being able to concentrate harder has knock-on benefits for overall mental performance, and it becomes all the more obvious why individuals with poor attention often show poor performance in other areas of activity.

We are beginning to understand better how the brain works and the role of sleep. Sleep is when your brain processes new information needing to be remebered, practises and hones new skills - and even solves problems.

When we have to get our heads around new challenges we often grind away, feeling like we are not making progress and getting more frazzled by the minute. In fact we would be better off working for a couple of hours, then stop racking our brains and go to bed. While asleep our brain will reactivate the circuits it was using as we worked on the material, rehearse the information and then shunt the new memories into long-term storage.

When you wake up, hey presto the cloud of uncertainty has lifted and you understand much better. This applies to skills such as playing the piano, driving a car even memorising facts and figures and problem-solving. Taking a nap after training can help consolidate new skills, says Carlyle Smith of Trent University in Peterborough, Ontario.

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…have a sleep!