There are plenty animals that have all but eliminated sleep; giraffes, elephants, dolphins to name a few, can get away with very short bouts of sleep. Others pe

There are plenty animals that have all but eliminated sleep; giraffes, elephants, dolphins to name a few, can get away with very short bouts of sleep. Others perfect the Unihemispheric slow-wave sleep, I've even seen studies that humans do this to a lesser degree when sleeping in unfamiliar surroundings. The majority of our hominid evolution was in Africa, where we likely developed night time sleep patterns as a defense to the big cats developing better night vision. Other benefits like social interactions, heat-conservation, even directly procreation; As well as the diminished usefulness of any work, from hunting to building in darkness would all play a roll. I find it fascinating that we likely also developed a fear of the dark as a response to the big cats developing better night vision in exactly the same way gazelles developed better hearing and faster legs.