We spend around a third of our lives sleeping. Considering how much time we spend doing it, you might think we'd know everything about it. But scientists are still searching for a complete explanation of why we sleep and dream. Subscribers to Sigmund Freud's views believed dreams were expressions of unfulfilled wishes – often sexual – while others wonder whether dreams are anything but the random firings of a sleeping brain. Animal studies and advances in brain imaging have led us to a more complex understanding that suggests dreaming could play a role in memory, learning and emotions. Rats, for example, have been shown to replay their waking experiences in dreams, apparently helping them to solve complex tasks such as navigating mazes
wow, smart rats