During sleep, our brains are flushed out to remove toxins, researchers found.

[riazur]

In tests on mice, researchers discovered that the harmful cell waste that accumulates in the brain while the cells are working is removed twice as quickly during sleep when the cells aren't working. That's because channels open up between the cells and flush waste away. This is the first major mechanical reason for why we need to sleep.

One of the toxins removed from the cells is the kind that builds up during Alzheimer's; understanding this not only helps us understand our need for sleep, and possibly control it better with drugs that turn it on and off, but could also lead to new ways to treat and prevent such diseases.