Rats, Stress, and Diseases of Adaptation
Almost four decades ago, endocrinologist Hans Selye made an important discovery in his lab – by accident. Selye intended to discover a new hormone by injecting some laboratory rats with estrogen. He administered – or at least attempted to, inject the rats with ovarian extracts. The Scientific American reports that Selye “would try to inject the rats, miss them, drop them, spend half the morning chasing the rats around the room or vice versa, flailing with a broom to get out from behind the sink, and so on” [1]. Comical as an image of a scientist chasing around – and being chased by rats this may be, Selye’s poor handling of the rats would lead to one of the psychological sciences’ most fortunate mishaps. Selye found no difference in whether the rats were part of the experimental (those injected with estrogen) or control groups; all rats from his experiment eventually displayed symptoms of illness, physical deterioration, and (sadly) died soon after. The rats’ exposure to frightening and stressful stimuli, environmental stress, and physical pain drastically weakened their immune system, leading to ulcers and their eventual death. This finding led Selye to propose that stressful, frightening – in fact, any instance of prolonged and recurrent unpleasant emotions can have the same effect on humans. He remarked that when we are unable to cope with demands that tax our physical and psychological resources and are faced with “diseases of adaptation.” We become susceptible to cardiovascular disease – heart diseases and high blood pressure, namely.

Feeling Bad Over a Prolonged Period Leads to Poorer Health
Countless research studies examining the links between stress and well-being show that our mental and physical health are closely intertwined. Diseases of adaptation are often studied as part of psychosomatic research – the term here referring to physical illnesses caused by or traced to internal mental or psychological states. Psychosomatic illnesses such as the cardiovascular diseases mentioned earlier, arthritis, osteoporosis and cancer have been linked to the weakened immune system functioning bought about by regular and prolonged experiences of stress. Stressful experiences, by themselves, are not necessarily detrimental to our well-being and health; some degree of stress motivates behaviours that help us move towards achievement and what psychologists refer to as goal-directed behaviours.

However, it is the prolonged state of stress that leads to detrimental health outcomes [2]. In a review of the now-expansive research literature on the causes of psychosomatic illnesses, researchers from the University of Ohio state that “distress-related immune dysregulation may be one core mechanism behind a diverse set of health risks associated with negative emotions” [3]. The experience of stressful situations and negative emotions accompanying such situations triggers the release of proinflammatory cytokines from immune cells, which, over time, is associated with the range of health complications above. Simply put, like the rats in Selye’s experiments, we too, experience the ‘wear and tear’ of our bodies and immune systems from experiencing stress in our lives. Distressing experiences weaken our immune system, making us vulnerable to a host of poorer health outcomes and worse of all, an untimely demise.

Building Resources for Better Mental and Physical Health
But enough about the bad news. Recent research in the area of psychoneuroimmunology (the study of how mental processes and health contribute to resistance against diseases) suggests that, inasmuch as prolonged negative emotions have a deleterious effect on our health, there are too, factors that lead to better mental and physical well-being. One promising area of research is based on psychologist Barbara Fredrickson’s broaden-and-build theory of positive emotions [4]. Fredrickson proposes that in contrast with negative, unpleasant emotions that elicit short-term survival and defensive responses, positive, pleasant emotions function to broaden the scope of our attention and build the necessary psychological resources for optimal functioning. One study examining the long-term effects of the build function of positive emotions show that individuals higher on trait positive affect (individuals more likely to experience and be susceptible to positive emotions and moods) showed lowered levels of proinflammatory cytokines. The study also showed that individuals experiencing the positive emotion of awe showed the greatest decrease in proinflammatory cytokines [5].

Recent studies have also shown the specific ways – and reasons why positive emotions have such a beneficial effect on physical health. Christian Gloria and Maria Steinhardt showed in their study of postdoctoral research fellows that the experience of positive emotions enhanced resilience by encouraging greater use of adaptive coping strategies. That is, experiencing positive emotions increases our resistance to stress by encouraging us to adopt healthier, more effective ways of coping with our challenges [6]. In another study, researchers sound that being self-compassionate – that is, being kind, accepting and mindful towards one’s challenges – was also associated with greater resilience. The study found that self-compassion served as an adaptive response to negative emotions; making that decision to be kind and accepting towards ourselves buffered against the effects of our stressful experiences [7]. Finally, a meta-analysis sampling close to 20,000 participants showed that individuals who are more emotionally intelligent – and those with higher emotional intelligence ability – were also likely to enjoy better psychosomatic and physical health [8]. Perhaps these findings should come as little surprise. The regular experience of positive emotions, the decision to be kind and compassionate toward oneself, along with the intelligence to discern between the effects of stress and distress all contribute to our ability to weather the demands imposed on our lives.

We Are What We Think (and Feel)
The promising research linking the effects of positive emotions, coping and positive psychology skills such as self-compassion tell us that while we will never be completely immune to stress’ effects on our health, there are skills that we can develop for better mental and physical health. We are what we eat – many a New Year’s resolution will revolve around decisions to eat more healthily and exercise more regularly. But perhaps, our health is also dependent on what (and how) we think and feel. Setting resolutions that enhance positivity in our lives might even make your goals more motivating and encouraging. Why not make the decision to be kinder to yourself? Why not set aside time for friends that can offer that social support? Why not cultivate a more optimistic mindset when you face your next challenge or hurdle? And of course, why not engage in that guilty pleasure you’ve been restricting yourself from enjoying because of your hectic work schedule. That license to engage in leisurely pursuits is, after all, supported by science – leisurely activities that rouse positive emotions are essential to our restoration and vitality [9]. And in the long run, your body will thank you for making the conscious effort to de-stress.