People spend about a third of their lives asleep. Yet, surprisingly little is known about how our brains control falling asleep and waking up. Now, researchers led by Prof. Henrik Bringmann at the Biotechnology Center (BIOTEC) of TUD Dresden University of Technology discovered another piece of this puzzle. The team showed that a single brain signal acts like a biological switch—both triggering sleep and ending it.

Their findings, published in the journal Current Biology, were made possible by studying a tiny roundworm, C. elegans, a powerful model organism in biology.

“It is really important to be able to fall asleep, but just as important to wake up too,” says Prof. Bringmann, research group leader at BIOTEC who led the study.

The brain is a unique place. It is shielded from much of the body by the blood-brain barrier, meaning it’s protected from pathogens and potentially dangerous substances that might be in our blood. And historically, many scientists believed that separation extended to the immune system as well: the brain has its own specialized immune cells called microglia, but immune cells present in the rest of the body were long thought to steer clear of the brain unless there was a disease or other problem requiring their presence.

Now, a team of scientists from Yale School of Medicine (YSM) has shown that immune cells known as T cells reside in the healthy brains of mice and humans, trafficked there from the gut and fat. This is the first time T cells have been shown to inhabit the brain under normal, non-diseased conditions.

The findings are published in Nature.

Published in Brain, Behavior and Immunity—is the first to suggest that a tumor-driving gene known as AEG-1 actively regulates the inflammation responsible for causing chemotherapy-induced peripheral neuropathy (CIPN), a common and painful side effect of cancer treatment. Eliminating the function of this gene using targeted therapies could become a critical strategy for managing a debilitating side effect experienced by many cancer patients.