10 Things Your Body Does That Science Can't Explain

Sleep is a pretty weird thing, and not one that we understand all that well.

Sleep's ability to "energise" us is weird enough, despite the fact that this is what most people view as its primary function.

The human body gets its energy from food and the amount of energy "saved" by a good night's sleep is tiny, just about 50kcal, and is far outweighed by the amount of energy being used up as you sleep just to keep you alive. So it's not really as though sleep is for "energy" in the usual way we would think.

It is thought that sleep is a way of maintaining proper brain function, allowing it to perform maintenance without simultaneously having to deal with sensory input as it would when you're awake.

It is also thought that this is what is behind dreaming. Dreaming allows us to process our experiences from the safety of a dream world, meaning that we don't have to deal with the hormone levels that would usually be caused by a frightening or upsetting experience, and allowing our brains to log it away and learn from it properly. This is why you can wake up from even the most terrifying dream and not remain scared by it for any longer than a couple of seconds.

If we don't sleep, our brain function quickly begins to deteriorate. In fact, just 17 hours awake will bring brain function down to levels similar to how it is when over the legal drink driving limit.

Extended periods of sleeplessness will eventually cause disorientation, hallucinations and eventually death. The world no-sleep record currently stands at 11 days, and by the time those 11 days were up, Randy Gardner, the test subject, was convinced that he was a famous footballer.