Defragging Your Brain

Researchers have found our brains clean themselves during sleep.
Scientists long thought that one of the functions of sleep was to restore and repair the brain, and now research in the journal Science has found the brain's cleaning activities increases 10-fold during sleep, helping to remove the day's toxic clutter.
Researchers found the brain fluid flushes out rubbish twice as fast when asleep as when awake. This clean-up is so energy-intensive it would hinder our thinking if done when we were awake (rather like running a defrag computer programme while in the midst of some other work). They conclude that unlike the rest of the body - which depends on the lymphatic system to drain toxins - the brain has its own separate method of rubbish removal.
University of Auckland senior anesthesiology lecturer Dr Guy Warman says the research is very exciting, as there've been theories about why we sleep for a long time. He says an important implication is, if someone doesn't get enough sleep, the toxic build-up could mount and have health consequences. The number of hours a person needs to sleep to avoid a chemical build-up depends on the individual. But, generally, eight hours of sleep each night is needed for a good, restorative sleep.
However, explain this: if my brain DOES defrag every night…then how come it's STILL full of crap??!!