Many of us treat social connection as a luxury. Something that is good for happiness and mental health, but not quite in the same category as exercise, sleep, or nutrition.

That's despite the fact that research shows people with warmer, more satisfying relationships tend to live longer, stay healthier, and maintain better mental function with age.

New research suggests that oxytocin (the "cuddle hormone") may explain some of this longevity effect. It positions oxytocin as more than a feel-good chemical that spikes during intimate social bonding, but as a key regulator of the body's calm-and-connection system that helps translate closeness, care, and social safety into effects on stress biology, inflammation, and aging itself.

Oxytocin levels decline with age, leading to epigenetic remodeling, mitochondrial dysfunction, and chronic inflammation. Restoring oxytocin levels effectively reverses these changes.

This points to a profound idea: cultivating strong social ties throughout adulthood could mitigate this loss of oxytocin signaling and promote robust health and resilience against stress and disease.

As sterile-sounding as it might seem, it's a strong argument to think about intimate bonds and social interactions as pro-longevity interventions. They're not optional if we want to age successfully, and they need to become part of your "personal hygiene" like diet, sleep, and exercise.

Today's newsletter centers on a recent article that truly reshapes how I'll think about the power of social connection going forward. And I think it will do the same for you.

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Oxytocin declines with age

Oxytocin is a neuropeptide that acts as a hormone and a neuromodulator, and it influences a multitude of human social behaviors, including the stimulation of uterine contractions during labor, lactation, and the initiation of mother–infant bonding. Because of these and other functions, oxytocin is (over-simplistically) referred to as the "cuddle hormone." But the biology runs much deeper than that.

A new commentary centers on the findings of a recent study by Maejima and colleagues,¹ who showed that aging, DNA methylation, mitochondrial dysfunction, and inflammation form a vicious cycle that reduces oxytocin production. Administering oxytocin intranasally interrupts this cycle by promoting epigenetic remodeling, specifically demethylation through an enzyme known as TET2, effectively restoring mitochondrial function and suppressing systemic inflammation.

In the study, old mice had lower oxytocin levels, fewer oxytocin-positive neurons in the hypothalamus, and higher levels of the inflammatory marker high-sensitivity C-reactive protein (hs-CRP) than young mice. Aging was also associated with lower expression of TET demethylation enzymes and lower expression of mitochondrial proteins in both the hypothalamus and hippocampus, all pointing to an aging brain that was becoming progressively more methylated, inflamed, and energetically impaired.

What makes the paper especially striking is how quickly some of these changes reversed. Just 10 days of intranasal oxytocin restored plasma oxytocin to youthful levels and lowered hs-CRP. It also increased the number of oxytocin-positive neurons, restored TET2 expression, enhanced mitochondrial proteins, and increased expression of O-GlcNAc transferase, or OGT, a key cofactor that works alongside TET2 to promote demethylation and has been linked to cognitive rejuvenation in the aged hippocampus. In other words, oxytocin appeared to push on an entire anti-aging network.

These anti-aging effects were shown to be mediated through oxytocin receptors, because mice lacking oxytocin receptors had even lower levels of TET2, mitochondrial proteins, OGT, and DNA demethylation markers than wild-type mice, alongside visible signs of aging such as graying hair and greater body weight. That matters because it strengthens the causal argument that oxytocin’s benefits depend on oxytocin receptor signaling. As the commentary puts it, “... nasal administration of [oxytocin] acts as a powerful, non-invasive anti-aging intervention.”

(On a separate but related note, there's some fascinating research that sleep deprivation triggers the onset of a "loneliness phenotype" by inducing critical changes within the brain that alter behavior and emotions. The end result is that people who are sleep-deprived avoid social interaction, and their standoffishness is recognized by other people who, in turn, shun the sleep-deprived people as if they were ill, creating a vicious cycle of loneliness. Could this potentially explain part of the link between short sleep and poor health?

In the clip below from FoundMyFitness episode #45, Dr. Matthew Walker describes how sleep deprivation promotes this kind of "viral" loneliness).

Oxytocin and lifelong health

This single study is part of a much larger oxytocin story, one that expands into a lifecourse perspective on how the hormone shapes both bonding and the trajectory of aging itself. 

The core premise is that early closeness, care, and intimate social interaction activate oxytocin neurons in the brain, stimulate future social interactions, dampen the body's stress-response system, reduce inflammation, promote growth and restoration, and enhance immune and metabolic health. This framework positions oxytocin as a long-term regulator of healthy aging and longevity. 

The commentary takes us through the role of oxytocin at each stage of life. 

It begins at birth and infancy, when closeness and maternal care stimulate sensory nerves that activate and shape an infant’s oxytocin system, what the authors call the “calm-and-connection” system.

• These early experiences appear to have both immediate anti-stress effects and longer-lasting developmental effects that may persist into adulthood. What is especially interesting here is the idea that the amount of oxytocin we are exposed to early in life may help establish a kind of baseline oxytocin system function that carries forward.
• High levels of maternal care appear to strengthen the system, whereas deprivation or neglect may disrupt it and potentially accelerate age-related oxytocin decline. Early life experiences, in other words, may shape later-life function, and it all happens through epigenetic programming (as suggested by the elegant mouse study described above).

Into adulthood, the oxytocin system remains engaged through continuous social interactions and closeness. This is where the commentary introduces an incredibly compelling idea that every meaningful social interaction can be viewed as an “epigenetic maintenance event.”

• Because it was shown that oxytocin signaling helps maintain TET enzyme activity and DNA demethylation, the authors argue that regular social engagement may be biologically required to preserve oxytocin neuron function. It is, quite literally, a use-it-or-lose-it system. 
• Without repeated activation, oxytocin and related genes may become progressively hypermethylated, accelerating the epigenetic aging of the oxytocin system. When that happens, we lose social ease, emotional buffering and, important to our discussion today, oxytocin’s anti-inflammatory, cardioprotective, immune, and metabolic benefits.

There's evidence to support both sides of that equation. Adults who have experienced the loss of two or more parents, siblings, partners, or children at any stage of life show accelerated biological aging compared with those who have not experienced major loss.² Breastfeeding, one of the most physiologically potent natural triggers of oxytocin release, has been associated with lower maternal risk of breast cancer, ovarian cancer, type 2 diabetes, hypertension, cardiovascular disease, coronary heart disease, and stroke, with several studies suggesting a dose-response relationship—the longer women breastfeed, the more they are protected against some of these conditions.³

All of this evidence accumulates into a clean framework for how oxytocin may regulate aging across the lifespan. Early-life oxytocin activation may establish a healthier, more demethylated state in oxytocin neurons and perhaps in stress-response genes, reducing lifelong stress reactivity. 

Ongoing social bonds and intimate experiences continue to shape that system in either a positive or negative direction. Supportive relationships may help maintain oxytocin-mediated stress buffering, while traumatic relationships, chronic stress, and social isolation promote oxytocin decline, greater methylation, more inflammation, and a stronger stress response. 

Inflammation's underlying role

Here is where the paper becomes especially interesting to me. It identifies inflammation as a kind of "common currency" by which oxytocin may exert many of its beneficial effects. Oxytocin helps maintain the expression of these demethylation enzymes, which in turn may prevent chronic low-grade inflammation, or "inflammaging," from accelerating epigenetic aging, oxidative damage, and metabolic dysfunction. Oxytocin becomes a molecular link between relationships, inflammation, epigenetic drift, and aging biology.

So depending on the quality of our social interactions, we may be shaping far more than mood or emotional well-being. We may be shaping our epigenetic landscape. That is why the commentary concludes by reframing social connection as a form of “epigenetic medicine.” It is a provocative idea, but one that can also turn the soft, warm side of love and relationships into something cold and biological. But it fits surprisingly well with the mechanisms described here. 

In addition to the familiar drivers of genetic and epigenetic damage, such as toxins, inactivity, and poor diet, we should also take seriously the biological consequences of inadequate "social maintenance." We need to exercise the oxytocin system, not unlike how we exercise the heart or skeletal muscle. Or, as the commentary concludes:

“We are profoundly social creatures, and our relationships literally shape the pace at which we age. Supporting the oxytocin system across the lifecourse—from the first maternal touch to the last embrace—may be among the most powerful health-promoting interventions available.”

Uvnäs-Moberg, K., et al. Oxytocin, Epigenetic Aging, and the Social Regulation of Health: A Lifecourse Perspective on the Maejima et al. Findings.” Aging Cell (2026). doi: 10.1111/acel.70363.

Final thoughts

Our list of things that keep us biologically healthy does not usually include “call your mom” or “have lunch with a friend.” We tend to reserve the language of intervention for exercise, sleep, diet, and supplements, while treating connection as something emotionally nice but biologically optional. 

This new commentary argues for a very different view. Social bonding events may be recurring forms of biological maintenance—small but meaningful inputs that help regulate stress, inflammation, and even the pace at which we age. Of course, we have to acknowledge the elephant in the room… this biology has yet to be demonstrated in humans. But the wider literature is compatible with the idea that social ties determine how well (or how poorly) we age, and The Harvard Study of Adult Development—one of the longest-running longitudinal studies of human health and well-being—is perhaps the best example.⁴

It began in 1938 and originally followed 724 men from two very different groups: Harvard undergraduates and boys from Boston’s inner-city neighborhoods. Its most famous conclusion? Close, high-quality relationships are among the strongest predictors of long-term health and happiness. Across the study, people with warmer, more satisfying relationships tended to live longer, stay healthier, and maintain better mental function as they aged, whereas loneliness and chronic relational strain were associated with worse outcomes. 

Robert Waldinger, the study’s current director, has repeatedly emphasized that what keeps people healthiest over the long run is not wealth or fame, but the strength of their connections with others.

When we combine that with the molecular-level findings on oxytocin's role in aging, it becomes clear that socializing is not a distraction from health. It may be part of the machinery that sustains it.

Warm regards

— Rhonda and the FoundMyFitness team