I've always been interested in optimizing immune system function because I get sick every winter. Viruses that cause colds, flu, and related respiratory infections are not highly sensitive to drug therapy, so in most cases, the immune system is all we have. And sometimes I think I catch every virus that comes to town. Things could be worse; I'm happy I don't have an autoimmune condition. But I would really like to get through the winter with a minimum of illness.
For many years I got sick right around Christmas, shortly before or after the annual trip to visit my in-laws. Mostly it was after the trip, so I could blame the viruses from all over the country that I encountered in the airports and on the airplanes. In the winter, we spend more time indoors in crowded conditions, and thus have more chance to spread whatever germs we pick up. In addition, we have less sunlight to help us produce vitamin D and possibly kill airborne viruses. But is there something more about winter?
A recent article in the medical literature examines the effects of stress on the immune system. Stress can be any challenge to our homeostasis. This technical term means stability or equilibrium. The author notes that short term stress, on the scale of minutes or hours, actually improves our immune function. This is an adaptation, he suggests, to physical fight or flight challenges that may result in wounding and infection.
Chronic stress, on the time scale of weeks or months, is often immunosuppressive. The stress hormone cortisol is closely related to the steroidal anti-inflammatory cortisone; the two are rapidly inter-converted in the body. There is a complex system of molecular signals that changes to reduce our defenses against infection and cancer when we are exposed to long term stress. Unfortunately, this mechanism does not work to reduce autoimmune systems. The effects of stress on the immune system are more complicated than turning the dial up or down; immunoregulation is a key process that is disturbed by long term stress.
I take this to be a good reason to set boundaries during the holidays. It's inevitable that our normal routines are going to be disrupted.