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Kelli Harding M.D., MPH
Kelli Harding M.D., MPH

Is the Answer to All Our Stress and Illness More Kindness?

Decades of research support ‘the rabbit effect.’

Kelli Harding, MD, MPH
'The Rabbit Effect'
Source: Kelli Harding, MD, MPH

It was one of those mornings. You know the kind, where you land at work stressed out with a blinding headache after a series of seemingly random, rude incidents.

After sleeping through our alarm, my husband and I both woke up cranky. Still in my PJs, scrambling to get the kids ready for school, I feel criticized for something I was unaware I did. Waiting for coffee at a local bodega, a woman cuts in front of me in line and then gives me the stink-eye. Looking at my phone, I spy a social media post of friends at a party to which I wasn’t invited. My email offers a nasty-gram written in all CAPS from a coworker upset over a minor matter. He cc’d our boss. Then, I notice a conference invite includes a panel of experts that is yet another “manel” without a single woman or person of color.

And it’s only 8 a.m.!

If aggravating situations happen every so often, that’s one thing. But when “one of those days” becomes every day in your home, relationships, workplace, school, neighborhood, and broader community—it’s not just your good mood at stake, but your good health, too.

We know this in part because of some bunnies. Yes, bunnies.

In the late 1970s, scientist Dr. Robert Nerem and his team designed a straightforward experiment to clarify the relationship between diet and heart health. They fed nearly genetically identical rabbits the same high-fat diet. At the end of the study, they expected all the rabbits to have equal poor measures of health. Only they didn’t.

One group of rabbits had significantly better—60% better—health outcomes than the others. There was no explanation for the difference. Then Dr. Nerem noticed that the healthier rabbits were all tended by the same kind and caring young researcher. She frequently held the rabbits, talked to them, and played with them. In other words, she gave them kindness.

A radical idea emerged—could the social world change biology? The team decided to find out. They repeated the experiment with tightly controlled conditions and got the same startling results. Kindness made all the difference. This is what I call “the rabbit effect.”

As a doctor working in the emergency room, I thought this story made a lot of sense. It helped me understand what I saw clinically. Patients who fare the worse with illnesses often lack social supports.

People usually think of health in terms of diet, exercise, sleep, and doctor visits. Access to quality medical care, while critical, likely only accounts for about 10-20% of our overall health status. Even the influence of our genes is not as fixed as once believed. Four decades following Dr. Nerem’s initial study, ample research in public health, epigenetics, telomeres, and the neuroimmune system have revolutionized our understanding of health. In The Rabbit Effect: Live Longer, Happier, and Healthier with the Groundbreaking Science of Kindness, I describe in detail how our health is greatly impacted by our social world.

Here is the big takeaway—for us to thrive as individuals and communities, it’s time we put our emotional wellbeing first.

For those of us in the mental health field, we know no one exists in isolation. Every human being is part of a complex, interrelated system. We also see that mental health too often takes a backseat to physical health. Services are too few or too costly, or stigma prevents people from getting the care they deserve. According to the World Health Organization (WHO), only 1 percent of global aid goes towards mental health even though depression is the leading cause of ill health and disability worldwide.

Since overhauling the global health system seems overwhelming, what can we do?

You can cause positive change and boost the health of the people around you, whether you work in healthcare or not. It comes down to kindness. How we treat one another in every aspect of our day-to-day lives matters. Individual and collective health isn’t just happening at appointments in hospitals and clinics but also in our everyday experiences.

And here’s the best part: a single act of kindness isn’t necessarily a one-off. Instead, a kindness mindset can create a ripple effect of good. Just as a series of rude incidents can make us feel ill, cascading good acts help us thrive as individuals and communities. By recognizing all that we have in common, we have more power to shift destiny for ourselves and others than we may realize.

Sometimes I imagine a makeover to our world in the form of a movie montage, like in Rocky or Groundhog Day. How might our world transform if we all treated one another with dignity and kindness? Maybe if my morning had gone differently, I would have arrived at work in a better mood and been more willing to troubleshoot with a colleague instead of hiding out in my office. Maybe a kid sitting by himself in the cafeteria finds himself after a kind exchange with a classmate participating in the lunchtime Minecraft club. Or a father embraces his estranged adult son. A woman asking for change on the street finds herself in an apartment sitting down to a candlelit dinner with friends. Perhaps a vacant lot filled with broken glass becomes a grassy playground filled with kids. How can you imagine kindness transforming the world?

In 1902, author Henry James told his nephew, “Three things in human life are important. The first is to be kind. The second is to be kind. And the third is to be kind.” Now, over a century later, ample scientific evidence shows the quote could be speaking to our health and the health of our communities.

Kindness has tremendous power to buffer stress and help us live happier and healthier lives. How can you change someone’s life for the better today?


Nerem, Robert M., Murina J. Levesque, and J. Fredrick Cornhill. "Social environment as a factor in diet-induced atherosclerosis." Science 208, no. 4451 (1980): 1475-1476.

Hood, Carlyn M., Keith P. Gennuso, Geoffrey R. Swain, and Bridget B. Catlin. "County health rankings: relationships between determinant factors and health outcomes." American journal of preventive medicine 50, no. 2 (2016): 129-135.

“Depression,” Fact Sheet, World Health Organization (last updated March 22, 2018),

About the Author
Kelli Harding M.D., MPH

Kelli Harding, MD, MPH, is a psychiatrist in New York City specializing in mind-body medicine and the author of The Rabbit Effect: Live Longer, Happier, and Healthier with the Groundbreaking Science of Kindness.

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