The American lunch break is broken.

So finds a new survey from staffing company OfficeTeam, showing that 48 percent of employees say they spend less than 30 minutes on a lunch break. A full 9 percent say they take no break at all, and 29 percent of employees say they work during whatever lunch break they do take.

That many employees would opt to shovel food down their gullets while working through the day probably doesn't come as a surprise in the era of the always-on company. But it should pique your concern.

"Lunch breaks aren't just for eating--they provide time to clear your head and recharge," OfficeTeam executive director Robert Hosking said in a statement.

Indeed, ample evidence exists showing that uninterrupted work can squash productivity. The opportunity to go for a walk or to socialize with colleagues is something that should ultimately help your employees' performance.

Between expectations of legality and general decency, I assume you're not demanding your employees to work through lunch. But the survey shows that even if you aren't asking, they are.

Employees might think they'll look good for working straight through the day, or they might not be able to control their own workaholic nature.

Still, it might be worth it for you to let them know you expect them to take a lunch hour. You might also want to try establishing a more friendly or congenial lunchtime atmosphere--group outings, perhaps--in an effort to get your employees socializing and thus all the less likely to check their email on their iPhones.

Just like you can't force your employees to work through lunch, you can't force them to take one either. But by establishing that expectation you might ultimately reap the benefits of a more productive workforce.