Why You So Liddat is a show that explores the mind, our behaviour, and why we are the way we are. We know we need to sleep but at the moment, science isn't 100% sure on the reasons why we need to sleep. One school of thought suggests we sleep to conserve energy. Another looked at it from an evolutionary standpoint - to avoid the predators we couldn't see at night. Professor Richard Horner explored this in his book The Universal Pastime: Sleep and Rest Explained  and he speaks to us today on his theory on why we need to sleep.