Maybe it’s the extra exercise, the mental challenges, or simply a psychological effect, but older people who spend a lot of time with their grandchildren are healthier and live longer, a new German study has found.

Psychologist Ralph Hertwig and his colleagues at the Berlin-based Max Planck Institute for Human Development evaluated data from the Berlin Ageing Study, in which more than 500 people aged over 70 were interviewed between 1990 and 1993, and followed until 2009.

They found that half of the grandparents who looked after their grandchildren were still alive 10 years after the first interview, while half of those who didn’t – and also non-grandparents – died within five years.

“But it’s false to conclude that the more you help, the longer you’ll live,” Hertwig warns, noting that previous studies have shown no longevity benefits for grandparents who mind their grandchildren round the clock, which is stressful.

The tipping point varies from person to person. “It’s important to find a happy medium,” he says, adding that the motivation should be intrinsic. “Expecting something in return can quickly leave you frustrated if you get nothing.”

Erhard Hackler, managing director of the German Senior Citizens League (DSL) and a grandfather himself, says that caring for the little ones helps to keep him physically and mentally fit.

“You simply take part in everything, whether it’s playing tag or going swimming,” he says. “Without grandchildren, you probably wouldn’t do that.”

Nevertheless, he says there’s nothing wrong with not wanting to babysit all the time, and that you should be open about this with your child. “You can say: ‘We love the grandchildren, but we raised you and now need some space for ourselves.’”

People without grandchildren who nevertheless keep busy with other social commitments have also been found to have a longer life expectancy. “For a good, long life, the most important thing is to feel that you’re needed,” says Christoph Englert, a researcher at the Leibniz Institute on Ageing in Jena, Germany.

Having a sense of purpose is important in old age – whether it’s minding the grandchildren, or something else entirely. – dpa