If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.


Biological Chemistry

Sleep Helps Clean The Brain

Increased ability to clear the brain of metabolic byproducts may be behind the biological need for sleep

by Craig Bettenhausen
October 21, 2013 | A version of this story appeared in Volume 91, Issue 42

Credit: U Rochester Medical Center
Research collaborator Jeffrey J. Iliff explains the underlying mechanism for waste clearance from the brain that the team’s research has uncovered.

Sleep is a biological imperative for most animals. Even brief periods without sleep cause cognitive impairment, and long-term continuous sleep deprivation is a road through insanity that ends in death. Research reported in Science suggests that the restorative quality of sleep may be a result of an enhanced ability to eliminate potentially neurotoxic waste products in the unconscious brain (2013, DOI: 10.1126/science.1241224). Lulu Xie and Maiken Nedergaard of the University of Rochester Medical Center determined via electrochemical methods that a sleeping mouse’s brain is 23% intercellular space by volume. That value is just 14% in an awake mouse. The team observed that fluorescent tracers penetrated 20 times as far into the brains of sleeping mice as they did into those of mice that were awake. They also showed that the sleeping brains cleared amyloid-β, a protein implicated in Alzheimer’s disease, twice as fast as awake brains. The researchers propose that the increase in intercellular volume during sleep eases fluid flow through the brain to help flush out metabolic waste products that accumulate during wakefulness.


This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.