You’ve always suspected you caught a cold or flu after disrupting your sleep cycle (for example, after pulling that all-nighter). Now there’s proof: A study by Sassone-Corsi and colleagues has shown that maintaining the circadian clock boosts the body’s ability to fight intestinal bacteria infections. “Up to 15 percent of human genes, including those that respond to intestinal infections, are regulated by the day-night pattern,” Sassone-Corsi says. His research, looking at the salmonella pathogen, showed that the body’s immune system (which is governed by circadian-controlled genes) was better able to deal with the infectious agent in the daytime. Not only could this lead to more targeted timing for treatment of dangerous infections, but it could explain why disruptions in day-night patterns, such as travelling across time zones or doing shift work, raise our susceptibility to infectious disease, he adds.