geijlsngi15 Computer tests revealed that most of them struggled with mental agility tasks when they had less sleep, but the most interesting results came from the blood tests that were run.

Dr Simon Archer and his team at Surrey University were particularly interested in looking at the genes that were switched on or off in our volunteers by changes in the amount that we had made them sleep.

"We found that overall there were around 500 genes that were affected," Archer explained. "Some which were going up, and some which were going down."