Dogs are helping people regulate stress even more than expected, research shows
In a 2022 survey of 3,000 U.S. adults, more than one-third of respondents reported that on most days, they feel “completely overwhelmed” by stress. At the same time, a growing body of research is documenting the negative health consequences of higher stress levels, which include increased rates of cancer, heart disease, autoimmune conditions and even dementia.
Assuming people’s daily lives are unlikely to get less stressful anytime soon, simple and effective ways to mitigate these effects are needed.
This is where dogs can help.
As researchers at the University of Denver’s Institute for Human-Animal Connection, we study the effects animal companions have on their humans.
Dozens of studies over the last 40 years have confirmed that pet dogs help humans feel more relaxed. This would explain the growing phenomenon of people relying on emotional support dogs to assist them in navigating everyday life. Dog owners have also been shown to have a 24% lower risk of death and a four times greater chance of surviving for at least a year after a heart attack.
Now, a new study that we conducted with a team of colleagues suggests that dogs might have a deeper and more biologically complex effect on humans than scientists previously believed. And this complexity may have profound implications for human health.
How stress works
The human response to stress is a finely tuned and coordinated set of various physiological pathways. Previous studies of the effects of dogs on human stress focused on just one pathway at a time. For our study, we zoomed out a bit and measured multiple biological indicators of the body’s state, or biomarkers, from both of the body’s major stress pathways. This allowed us to get a more complete picture of how a dog’s presence affects stress in the human body.
The stress pathways we measured are the hypothalamic-pituitary-adrenal, or HPA, axis and the sympathoadrenal medullary, or SAM, axis.
When a person experiences a stressful event, the SAM axis acts quickly, triggering a “fight or flight” response that includes a surge of adrenaline, leading to a burst of energy that helps us meet threats. This response can be measured through an enzyme called alpha-amylase.
At the same time, but a little more slowly, the HPA axis activates the adrenal glands to produce the hormone cortisol. This can help a person meet threats that might last for hours or even days. If everything goes well, when the danger ends, both axes settle down, and the body goes back to its calm state.
While stress can be an uncomfortable feeling, it has been important to human survival. Our hunter-gatherer ancestors had to respond effectively to acute stress events like an animal attack. In such instances, over-responding could be as ineffective as under-responding. Staying in an optimal stress response zone maximized humans’ chances of survival.
