The 40-hour work week is an outdated model, according to Science Nordic's James W Vaupel, head of the new Danish Max Planck research center. Instead, he argues, we should only work 25 hours a week--but keep working until we’re octogenarians.

“We’re getting older and older here in Denmark. Kids who are ten years old today should be able to work until the age of 80. In return, they won’t need to work more than 25 hours per week when they become adults,” Vaupel told Science Nordic. “In the 20th century we had a redistribution of wealth. I believe that in this century, the great distribution will be in terms of working hours."

Vaupel is adamant that, in socio-economic terms, the important standard is the aggregate amount of work people do in their lifetimes, not at what point in their lives they do it.

Spreading out working hours over the full course of a person’s life, Vaupel argues, is both psychologically and physically beneficial at all stages of life.

A 25-hour work week will allow younger people to spend more time with their children, take better care of their health (which will help raise average life expectancy), and improve their over-all quality of life, while for the older population -- many of whom have more time on their hands than they know what to do with -- work can serve as both a psychological and physical outlet.

”There is strong evidence that elderly people who work part-time are healthier than those who don’t work at all and just sit at home,” Vaupel told Science Nordic.

Whatever you may think of this theory, there are certainly many who think (including Sheryl Sandberg) the status quo (the 40/50 hour work week) is not only detrimental to one's health, but actually not that productive.