Sheryl Sandberg, the second-in-command at social networking giant Facebook, admitted this month that she leaves work at 5:30 on the dot, and has done so ever since she had children. "It's not until the last year, two years, that I'm brave enough to talk about it publicly," she said. Her work habits stand in stark contrast to the all-consuming efforts of other high-powered executives, particularly in the hyper-competitive tech industry, where people often work 50, 60, or 70 — or more — hours a week. Should there be a 40-hour limit?

Yes. Working more than 40 hours hurts productivity: Workaholics "may think they're accomplishing more than the less fanatical worker," but studies show that "working more than 40 hours per week actually decreases productivity," says Geoffrey James at Inc. Overworked employees tend to turn in work "that must be scrapped or redone," and burned-out workers "inevitably start having personal problems that get in the way." In fact, six of the 10 most competitive economies in the world have made it "illegal to demand more than a 48-hour workweek." 
"Stop working more than 40 hours a week"

And long hours make us unhappy and unhealthy: The U.S. "is the most overworked nation in the developed world," and polls show that American employees are unhappier as a result, says Michael Janati at The Washington Times. Developed countries with shorter workweeks "place a much greater value upon strong relationships and prosperity as it pertains to their happiness." And the "sink or swim" environment in corporate America, which forces people to "perpetually work," can also lead to health problems like depression, chronic stress, and anxiety.
"A nation overworked; Abandoning happiness and health for paychecks"

But employees are to blame, too: "Whatever happened to 'work-life balance?" says Pete Cashmore at CNN. It's becoming "socially awkward to leave work at a time that used to be the standard," and it's not just bosses and management that are to blame. It's typical for modern workers to brag "about how little sleep" they get, as if it's a "badge of honor." The "measure of our work is in our productivity, not the number of hours we put in," and it's up to "both employers and employees to make living a healthy life socially acceptable again."
"Why it's OK to leave a tech job at 5 p.m."