This article originally appeared in MindBodyGreen.

The occasional (or seasonal) cold or flu is a natural part of life. But if you notice you're spending way more time laid up on the couch, taken out by yet another bout of sickness, it may be a sign that something isn't quite right. There are several reasons you keep getting sick. The good news? Many of them are within your control. 

1. You're experiencing chronic stress or anxiety.

Chronic stress (coupled with inadequate sleep) is the No. 1 reason people get sick, according to Heather Moday, M.D., an allergist and immunologist. "When we are run down and cortisol soars, our virus surveillance cells dip and we get sick more easily," she explains. "Cortisol itself interferes with the ability of specific white blood cells called T-cells to proliferate and get signals from the body. In addition, cortisol also lowers an important antibody called secretory IgA, which lines the respiratory tract and gut and is our first line of defense against invading pathogens."