One possible explanation has to do with how your immune system responds to short periods of stress. When you’re in a tense situation, your body releases stress hormones like epinephrine (a.k.a. adrenaline) and cortisol, which trigger a cascade of physical changes to help you power through. For example, your pulse and breathing speed up, and your immune system also goes on high alert, so you’re primed to handle the threat at hand without getting sick. In small doses, having a stress response is important, Dr. Lee explains: “We can all think of times when we had a deadline to hit or we needed to protect somebody we love, and a short burst of stress helped increase our focus and ability to get to the goal.” But as soon as the trouble subsides, that response flips off, which may affect your immune system too, Dr. Lee says. “When we leave those situations, it’s like we let our guard down both psychologically and biologically.” This swing in your immune function may be enough to leave you vulnerable to the virus du jour. People with migraine may experience a similar phenomenon known as a “let-down” or “weekend” migraine. The cause isn’t totally clear, but the main theory is that abrupt changes in hormone levels when a stressful period ends can trigger a migraine attack.
For anyone thinking, But I’m always stressed at work, it’s not just a pre-vacation thing, your immune system might be betraying you in a different way. Being chronically stressed can actually suppress your overall immune function, Purvi Parikh, MD, MD, FACAAI, FACP, a New York-based allergist and immunologist and a member of the medical advisory council of the Allergy & Asthma Network, tells SELF. So if you live most of your life in a frazzled state, you could be more susceptible to catching something—and work obligations might just keep you from noticing early symptoms. “Often, when we’re busy, we aren’t thinking about what’s going on internally so even if something is brewing, we may be more aware of it once we have stopped and aren’t distracted by the day-to-day grind,” Dr. Parikh says.
At the same time, the all-consuming demands of a packed work period can make it hard to keep up with your typical routine. Maybe you’re staying up later than usual, outright skipping meals or workouts, or eating less-than-nutritious foods. It’s easy to let go of the things you normally do to care for yourself in the name of “powering through,” Dr. Lee says. The problem is, a combo of missed sleep, poor nourishment, and lack of exercise can make you feel low-energy, moody, and generally unwell—even if you’re not actually sick. What’s more, these lifestyle changes also strain your immune system, opening the door for an infection to weasel itself in as soon as you peace out.
