In the absence of a good night's sleep a player's reaction time and focus can nosedive.
Sleep also gives the body a chance to heal and recover - instead of expending energy on keeping the body ticking over while you're awake, it redirects its resources to helping muscles and other tissues heal and recover.
More after the break
Liverpool's former head of sports medicine and science, Dr Peter Brukner, believes good, quality sleep can play a significant role in a player's performance.
But when is it most beneficial to sleep - before of after a game? Watch this video for Dr Brukner's verdict.
Dr Peter Brukner was talking at Leaders in Performance, part of Leaders in Football. For details on 2011’s conference, click here.