Here’s something that you are going to very tempted to tell your boss. According to 150 years of studies — yes, 150 — on productivity, having employees work more than 40 hours a week does more harm than good to the bottom line.

Writer Sara Robinson lays out the case against more than a 40-hour work week, explaining that research proves extra time on the clock makes workers tired, unproductive, and, in some cases, dangerous.

“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,” Robinson writes.

However, for whatever reason, employers have stopped using 40 hours as a guideline. Now, it’s not uncommon for people to log close to 55 hours a week on the job.

While there has been some research since the ’60s which suggests people can be productive working more than 40-hour weeks in very brief spurts, the rest of the data collected continues to confirm what was already known: working more than the traditional eight-hour days isn’t doing anybody any good.

[Salon]