Scientific American Sleep is such a large feature of our lives that it’s easy to forget how utterly weird it is. Every night, if we’re lucky, our brain cells switch into a synchronized pattern, putting our lives and minds on hold for hours. Sleep scientists have yet to fully explain why we spend a third of our lives in this state, let alone why we use some of that time wandering through vivid, nonsensical and sometimes upsetting hallucinations.
A recent study in Science suggests that sleep may serve to wash the brain of harmful waste products that build up during the day. Medical researchers observed an increased flow of cerebrospinal fluid in mice that were sleeping or anesthetized. This fluid carries away waste proteins, including one linked to Alzheimer’s disease. The findings join other theories on the function of sleep, some of which I discuss above, in our latest Instant Egghead video.