Research

How Your Brain’s Nightly Cleanse Keeps It Healthy

Illustration of person sleeping under the stars
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You can see it coming in right there, that little spot,” says neuroscientist and engineer Laura Lewis.

A remarkably bright pulsing dot has appeared on the monitor in front of us. We are watching, in real time, the brain activity of a graduate student named Nick, who is having an afternoon nap inside an imaging machine at the Massachusetts Institute of Technology, where Lewis has her laboratory.