Carol Graham researches what makes people happy.
She's found that the lowest times in peoples' lives occur when they are in their forties, but after that their life satisfaction improves. It's called the happiness u-curve and it is a pattern that's repeated all over the world, no matter what the socio-economic conditions of the country.
So why do people get unhappy in their forties, but then get happier in their fifties?
Carol Graham talks to Kathryn Ryan about happiness and well-being.
Carol Graham is a fellow at the Brookings Institution and a professor of public policy at the University of Maryland who has written several books about happiness, including one about the paradox of "happy peasants and miserable millionaires".