Pourquoi être gentil aide les autres et vous profite aussi

How kindness affects your body

Kindness can be practical, such as offering support or lending a hand, but it can also be quiet and everyday - showing patience, expressing gratitude, checking in on someone, or simply choosing empathy when it would be easier not to.

Dr Sadie Elisseou, a primary care physician and advocate for trauma-informed care in Greater Boston, USA, says kindness - like all human behaviours - can be understood through different lenses.

From a biological perspective, she explains, kindness can trigger a cascade of hormonal responses that reinforce it as a positive behaviour. When you perform an act of kindness, your body releases certain chemicals that influence how you feel, think and connect with others.

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• Ocytocine - often called the ‘love hormone’, this is released during close connection and bonding, such as breastfeeding, and plays a key role in forming social bonds.

• Dopamine - a feel-good chemical linked to pleasure and reward, which can contribute to what’s sometimes described as a ‘helper’s high’.

• Sérotonine - a neurotransmitter that helps regulate mood and contributes to feelings of wellbeing and emotional stability.

“These biological effects are also noted when we receive or witness kindness from others,” says Elisseou. “In essence, kindness is a built-in biological mechanism that helps humans feel good in connection with other humans - and thus supports our survival.”

The health benefits of being kind

Beyond the general feel-good vibes, research suggests that acts of kindness, in whatever form they take, can have positive effects on your health. These benefits aren’t limited to mental wellbeing - they can influence your physical health too.

Less stress, feel better

Our stress hormones aren’t designed to make us anxious - they actually help us succeed in certain situations.

Elisseou explains that while stress hormones can help you perform well on a test, too much stress can be toxic and harm your performance.

“Studies find that kindness reduces cortisol in a way that positively impacts health,” she says. “For example, less of the ‘bad stress’ means better cardiovascular health, improved immunity, and enhanced mental wellbeing.”

Mulpuri adds that lowering cortisol levels through acts of kindness can also réduire l'inflammation, improve sleep, and boost metabolic health, helping to prevent conditions such as diabetes.

“Kindness helps gently turn down that stress dial,” he says.

How kindness helps your heart

Oxytocin - one of the hormones released during acts of kindness - may help support heart health.

“Research shows that oxytocin can promote blood vessel relaxation and may help reduce blood pressure in some contexts,” says Mulpuri. “Studies have also found that oxytocin has anti-inflammatory properties, which could theoretically benefit cardiovascular health over time.”

He does note, however, that most of the evidence comes from studies where oxytocin is given in controlled settings - not from the natural boosts we get through normal social contact.

“What we can say more confidently is that positive social connections and supportive relationships are consistently linked to better heart health outcomes,” he adds.

“Who you surround yourself with matters. Whether oxytocin is the primary driver of this benefit, or just one of many factors, is still being researched.”

Could kindness help you live longer?

Some evidence suggests that acts of kindness may affect the body in ways that could even support a longer life.

Elisseou explains that numerous studies have found that strong social support - including positive, supportive relationships - is linked to a longer lifespan.

She says: “A growing body of research shows that kindness, empathy, and compassion can affect our bodies right down to our cells.”

Mulpuri agrees, noting that people who regularly engage in helpful behaviour towards others tend to live longer, develop fewer long-term health conditions, and maintain better cognitive function.

“Supportive, kind relationships strengthen these effects,” he says. “Humans are biologically wired for connection. Longevity isn’t just about what you eat or how much you exercise - it’s also about belonging, meaning, and mutual care."

Mulpuri adds that sustained positive social connections may be especially important. This is because they help buffer stress and reinforce feelings of safety and belonging, which can reduce long-term physiological wear and tear.

Long-term mental health benefits

As a physician, Elisseou says many of her socially isolated patients experience more symptoms of depression, anxiety, and la solitude.

She explains: “Conversely, those who are embedded in a strong social network, and those who contribute to causes they find meaningful, are more likely to be happier, take less psychiatric medicine, and struggle less day to day with mental health symptoms.”

Mulpuri adds that, in people with anxiety, acts of kindness can activate the parasympathetic nervous system (PSNS) and promote a sense of calm.

“In those struggling with dépression, it may increase the ‘feel-good’ chemical dopamine and reduce rumination by shifting focus outwards,” he says. “It also reinforces social connection, directly addressing loneliness.”

He notes that this applies to both sides of the exchange - people who give feel more meaningful and connected, while those who receive feel seen and valued.

“From a clinical perspective, engaging in prosocial behaviour is one of the most accessible interventions we can recommend for mental health support,” he says.