What can kindness do for you? Give you a warm glow perhaps, or a feeling of well-being? While that may be true, scientists and academics at a new research centre say it can do much more – it can extend your life.

The notion of kindness has made headlines recently.

Ahead of World Kindness Day this week, what does it actually mean to be kind – and why is it important?

This is what the experts want to examine. And they are deadly serious about it. After all, it could be a matter of life and death, they say.

Mr Fessler’s work has looked at how people can be motivated to be kind simply by witnessing acts of kindness – and working out who is affected by this “contagious kindness”.

“I think it’s fair to say we live in an unkind age right now,” he says. “Both domestically in the United States and around the world, what we are seeing is increasing conflict between individuals who hold different political views or belong to different religions.”

Kindness, he says, is “the thoughts, feelings and beliefs associated with actions intending to benefit others, where benefiting others is an end in itself, not a means to an end”.

And unkindness, on the other hand, is “intolerant beliefs, the lack of valuation of others’ welfare”.

Mr Fessler says that it’s known that bad stress – the kind where you can’t do anything about a challenging situation, as opposed to the “good” stress from challenging but satisfying activities, like rock climbing – is bad for you.

“Living with people who treat you, at best, with disregard or a lack of concern, and at worst with open hostility, is bad for you. It shortens your life, quite literally,” he says.

“Conversely, both receiving kindness from others, and providing kindness, both of those things are the antithesis of this toxic stress situation. And they’re good for you.”

Kindness, she says, can “turn a lot around and help people navigate things in their world”.

Tips for living a kinder life from kindness expert Gabriella Van Rij: