Have you ever suffered through a particularly stressful period in work or family life only to find that, as soon as you are able to relax, you have succumbed to every cold and flu virus going? This is probably because your body’s stress system and immune system are integrally linked.
When you are stressed your brain kicks off a process that readies your body to flee or to fight. As part of this the body stops all unnecessary systems like digestion and boosts anything that might come in useful like the immune system. Short-term stress (lasting for a few hours) can therefore protect the body from infection by giving extra resources to the immune system [1].
Remaining permanently in flight or fight mode, however, is not sustainable. We need to be able to digest and to relax when we are safe. Cortisol, the stress hormone, is thought to tell the body to produce more immune defences in times of stress and also to tell the body it can stop when you are relaxed. So what happens when you experience chronic stress? This seems to mess up the body’s ability to regulate the immune system. Cortisol doesn’t know when to turn the immune system off so it remains in a constant state of low-level readiness [1]. As with everything in life you can have too much of a good thing and a constantly primed immune system is just as unhealthy as an unprepared one leading to conditions such as dermatitis, cardiovascular disease and autoimmune diseases. In addition, the immune system becomes less able to fight normal infections.
Some studies have shown this in real-world settings. In relation to short-term stress, for example, researchers showed that medical students had lower levels of protective immune cells 24 hours after exams compared to during exams [2]. In relation to chronic stress, another study compared parents of chronically ill children with those of healthy children. The stressed parents of the sick children had a constantly turned on immune system that they couldn’t turn off [3].
Finally, the term Leisure Sickness has been used to describe the phenomenon whereby people fall ill on their holidays. This is something that 3% of the population report experiencing [4]. It is possible that stress may project your immune system until you go on holiday. However this is still a theory that has to be tested. It is also possible that when you are stress you do not notice the symptoms of ill health until you have less demands on you.
In short, stress can affect your immune system for better and for worse. The key, as with everything in life, is to keep a good balance so you can stay fighting fit.
- Dhabhar, F.S., Effects of stress on immune function: the good, the bad, and the beautiful. Immunologic research, 2014. 58(2-3): p. 193-210.
- Uchakin, P.N., et al., Immune responsiveness following academic stress in first-year medical students. Journal of Interferon & Cytokine Research, 2001. 21(9): p. 687-694.
- Miller, G.E., S. Cohen, and A.K. Ritchey, Chronic psychological stress and the regulation of pro-inflammatory cytokines: a glucocorticoid-resistance model. Health Psychology, 2002. 21(6): p. 531.
- Vingerhoets, A.J., M. Van Huijgevoort, and G.L. Van Heck, Leisure sickness: A pilot study on its prevalence, phenomenology, and background. Psychotherapy and Psychosomatics, 2002. 71(6): p. 311-317.
