The Carnegie Mellon team, headed by Sheldon Cohen, ran two tests of this theory. First they exposed healthy adults to cold viruses, isolating and monitoring for five days afterwards. People who’d recently been under stress showed increased resistance to cortisol. In a second test, the researchers found that participants had higher numbers of cytokines, which trigger inflammation.
So what does it all mean? That when you get stressed out and stop sleeping, or stop sleeping well, you get sick. (Think back to college, when you’d get a horrible flu or even pneumonia or mono, right after finals were over.) That probably doesn’t seem that concerning; we’ve dealt with the post-all-nighter flu all our lives. But this year has also seen convincing research that the body’s immune response is key to protecting us from serious disease, such as cancer, and that inflammation is a key precursor to heart attack, stroke, diabetes, and other life-threatening diseases. In fact, ongoing research is underway to document the effects of stress and sleep loss on shortening lifespan.