These days, it’s not uncommon for employees to stay at their desks during their lunch hours and eat their midday meals while they continue to work. But is that really the best use of their time?

Workweek lunches have generally always been quick affairs — dash out, grab a bite and dash back — but today’s longer work hours and lower job security mean the custom is quickly disappearing.

In 1990, a Gallup Poll found that more than half of Americans took at least 30 minutes for lunch, but now, only a third leave their desks to do so. Even executives seem to have ditched the time-honored tradition of brokering deals over a “power lunch” — a 2011 survey conducted by CareerBuilder found they’re now are twice as likely to bring lunch from home instead of going out.

But is that really resulting in higher productivity? Not according to Kimberly Elsbach, a management professor at UC-Davis who studies workplace psychology.

“Never taking a break from very careful thought work actually reduces your ability to be creative,” she says. “If you’re skipping lunch to continue to push forward in a very intense cognitive capacity, then you’re probably not doing yourself any favors.”

[Time]