Exploring the physiological effects of thinking positively

Whereas countless studies have examined the effect of negative psychological states on levels of cortisol – a corticosteroid hormone that is associated with stress and ill-health – few, if any, have looked at the effect of positive psychological states on the hormone, a fact that Julian Lai (City University of Hong Kong) and colleagues see as part Western society’s disease-oriented view of health that “places disease and health on two opposite ends of a continuum and defines the two states as presence and absence of negative conditions, respectively”.

In an effort to rectify this bias, Lai’s team recruited 80 healthy adults, took saliva samples from them six times a day for two days (for measuring cortisol levels), and asked them to complete questionnaires about their optimism/pessimism and their mood over the last month and the last day.

They found that in men only, optimism was associated with lower cortisol levels after waking up, when levels of the hormone tend to peak as part of a daily cycle. The researchers said more research was needed to explain this gender difference. In men and women, they found that a generally positive mood during the last month was associated with lower cortisol levels over the whole day, even after controlling for good or bad mood on the day of testing.

The researchers said their findings “may draw increased attention to the potential impact of positive psychological dispositions or conditions on cortisol secretion and thus initiate a shift of research focus to the physiological substrates of positive states of minds…”. Future work should investigate whether the effects of positive psychological states on cortisol levels, as reported here, have actual health benefits, the researchers said.

Lai, J.C.L., Evans, P.D., Ng, S.H., Chong, A.M.L., Siu, O.T., Chan, C.L.W., Ho, S.M.Y., Ho, R.T.H., Chan, P. & Chan, C.C. (2005). Optimism, positive affectivity, and salivary cortisol. British Journal of Health Psychology, 10, 467-484.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Link to the Positive Psychology Centre
Link to special issue of The Psychologist on Positive Psychology (free access)