Study finds married people have lower levels of stress hormone

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Married individuals tend to have lower levels of the stress hormone cortisol, according to research published in the journal Psychoneuroendocrinology.

Previous research has shown that married people tend to be healthier than both the previously married and those who never married. However, the biological reason this was the case remained unclear.

The new study of 572 adults suggests that stress is one mechanism. The researchers found that married individuals had lower cortisol levels, a physiological indicator of lower levels of stress. Married individuals also had steeper daily cortisol slopes. Cortisol levels peak when a person wakes up and decline during the day. Quicker declines are associated with better health.

PsyPost interviewed the study’s corresponding author, Brian Chin of Carnegie Mellon University. Read his responses below:

PsyPost: Why were you interested in this topic?

Chin: Previous studies demonstrate that married individuals tend to be healthier than those who are single, divorced, widowed, or separated. However less clear are the psychological and biological mechanisms through which this occurs. To this end, recent research has focused on how unmarried individuals may experience either more stress or different types of stress than married people which would then put them at risk for poorer health outcomes.

One pathway through which stress is thought to affect health is via the hypothalamic–pituitary–adrenal axis. In our study, we wanted to assess HPA axis activity by measuring cortisol – a hormone that regulates numerous metabolic and immunological processes in the body. In other words, we were really interested in examining cortisol as one potential biological mechanism through which marital status affects health.

What should the average person take away from your study?

We examined cortisol in 572 healthy adults between 21-55 years old. Consistent with our hypotheses, we found that participants who were married had lower cortisol outputs and steeper cortisol slopes than those who were either never married or previously married. This makes sense – both lower cortisol outputs and steeper daily slopes have been shown to be associated with better health outcomes. Our study provides some of the first evidence that cortisol may be one biological pathway through which our romantic relationships can get under the skin to affect health.

Are there any major caveats? What questions still need to be addressed?

Future studies should continue to explore other physiological pathways through which these health effects occur. Cortisol is presumably not the only biological mechanism through which marital status affects health. More research is also needed to clarify the factors associated with marriage that are important for physical health. Finally, future work should continue to explore how other types of romantic relationships (e.g., cohabitation without marriage) affect health and biological markers of health.

The study, “Marital status as a predictor of diurnal salivary cortisol levels and slopes in a community sample of healthy adults“, was also co-authored by Michael L. M. Murphy, Denise Janicki-Deverts, and Sheldon Cohen.