Ivanov and his collaborators were recently awarded a $1 million grant to advance their work in the emerging field of network physiology, reports BU Today, of which sleep plays a role.

During deep sleep, they found, most of the body’s systems seemed to be disconnected. But new linkups suddenly switched on when each subject shifted into REM sleep. Even more connections flipped on for light sleep until, when subjects woke up, all the connections were suddenly illuminated. His team was astonished to find how quickly the communication network could be rearranged, Ivanov recalls. Though researchers had expected that the body’s “network topology”—that is, the shape of a map that represents its connectivity—would change over hours or days, no one had anticipated that it might change in a matter of seconds.