Research shows that consistently working more than 40 hours a week is simply unproductive.

For many in the entrepreneurship game, long hours are a badge of honor. Starting a business is tough, so all those late nights show how determined, hard working and serious about making your business work you are, right?

Wrong. According to a handful of studies, consistently clocking over 40 hours a week just makes you unproductive (and very, very tired).

That's bad news for most workers, who typically put in at least 55 hours a week, recently wrote Sara Robinson at Salon. Robinson's lengthy, but fascinating, article traces the origins of the idea of the 40-hour week and it's downfall and is well worth a read in full. But the essential nugget of wisdom from her article is that working long hours for long periods is not only useless – it's actually harmful. She wrote:

The most essential thing to know about the 40-hour work-week is that, while it was the unions that pushed it, business leaders ultimately went along with it because their own data convinced them this was a solid, hard-nosed business decision…. Evan Robinson, a software engineer with a long interest in programmer productivity (full disclosure: our shared last name is not a coincidence) summarized this history in a white paper he wrote for the International Game Developers’ Association in 2005. The original paper contains a wealth of links to studies conducted by businesses, universities, industry associations and the military that supported early-20th-century leaders as they embraced the short week. 'Throughout the ’30s, ’40s and ’50s, these studies were apparently conducted by the hundreds,' writes Robinson; 'and by the 1960s, the benefits of the 40-hour week were accepted almost beyond question in corporate America. In 1962, the Chamber of Commerce even published a pamphlet extolling the productivity gains of reduced hours.' What these studies showed, over and over, was that industrial workers have eight good, reliable hours a day in them. On average, you get no more widgets out of a 10-hour day than you do out of an eight-hour day.

Robinson does acknowledge that working overtime isn't always a bad idea. "Research by the Business Roundtable in the 1980s found that you could get short-term gains by going to 60- or 70-hour weeks very briefly — for example, pushing extra hard for a few weeks to meet a critical production deadline," she wrote. But Robinson stressed that "increasing a team’s hours in the office by 50 percent (from 40 to 60 hours) does not result in 50 percent more output…In fact, the numbers may typically be something closer to 25-30 percent more work in 50 percent more time."

The clear takeaway here is to stop staying at the office so late, but getting yourself to actually go home on time may be more difficult psychologically than you imagine.

As author Laura Vanderkam has pointed out, for many of us, there's actually a pretty strong correlation between how busy we are and how important we feel. "We live in a competitive society, and so by lamenting our overwork and sleep deprivation — even if that requires workweek inflation and claiming our worst nights are typical — we show that we are dedicated to our jobs and our families," she wrote recently in the Wall Street Journal.

Long hours, in other, words are often more about proving something to ourselves than actually getting stuff done.

Are your 55+ hour weeks really productive and sustainable?

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