So here is an amazing new discovery in neurology: the brain cleans itself. At least, the brains of mice do, as shown in this study. It hasn’t been observed in humans yet, but since nearly all animals sleep, there’s a good chance they do it for the same reasons. This could explain so much, like why people perform so poorly at all sorts of tasks when they’re sleep deprived and why sleep is critical for memory formation (and thus, learning). It may even explain why people get headaches and feel sick when overtired; if you don’t sleep well enough, then the neurotoxins just build up in the brain. Of course, because diseases like Alzheimer’s and Parkinson’s are correlated to sleep problems, scientists will undoubtedly begin to study how well the brains of patients with those diseases clean themselves. For a good summary of the study’s findings, see this article on NPR.