Your brain fills up with junk all day, and it’s more tangible than the endless stream of content you feed it. It’s stuff like proteins and cellular debris; byproducts of its natural processes that it needs to occasionally sweep out, the way your body eventually, uh, evacuates meals. According to a growing mountain of research, if the brain doesn’t properly flush out some of that garbage, it may contribute to neurodegenerative diseases like Alzheimer’s disease. Sleep has long been considered the brain’s nightly cleaning cycle. But a new study from researchers at Pennsylvania State University suggests another surprisingly effective maintenance tool: just moving your body around a little. Videos by VICE The findings, published in Nature Neuroscience , describe the human body as something of a giant septic tank that occasionally needs to be cleared out.…