"Work hard and you will get ahead," is an idea that's baked into the American mindset -- it's practically a cornerstone of our society.

It also bears out in our actions. Americans work an average of 34.4 hours a week, according to a 2015 CNN story citing Gallup data. That's more than workers in the world's largest economies. In addition, adults working full time report that they work an average of 47 hours each week, and nearly 40% report putting in more than 50 hours at work each week.

Hard work can pay off, but there are limits. At some point working harder produces diminishing returns and working fewer hours would actually be more productive.

A woman sleeps at a desk with a computer and coffee cups on it.

There are some obvious signs you are working too many hours. Image source: Getty Images.

How much is too much?

How much work is optimal depends on the type of work you do, and your own personal make-up. I, for example, can get by on just a few hours sleep while my wife rapidly loses her ability to function if she does not get her normal hours.

In a broad sense, however, there are some guidelines, and the numbers may shock you. A study done at the Australian National University (ANU) showed that 39 hours is the optimal amount people should work. The study's lead researcher, Dr. Huong Dinh from the ANU Research School of Population Health, said "the healthy work limit for women should be 34 hours per week once their other commitments were considered." The number was higher for men at 47 hours a week.

"Despite the fact that women on average are as skilled as men, women on average have lower paid jobs and less autonomy than men, and they spend much more time on care and domestic work," Dinh said. "Given the extra demands placed on women, it's impossible for women to work long hours often expected by employers unless they compromise their health."

What happens when you work too much?

In addition to your work suffering, putting in too much time at the office can actually be bad for you.

"Long work hours erode a person's mental and physical health because it leaves less time to eat well and look after themselves properly," Dinh said.

Spending too much time working can cause everything from minor pains due to sitting at a desk too long to serious consequences like a greater risk of a heart attack due to stress. Being at work too much can also weaken your personal relationships, cost you friends, and generally harm your bonds with everyone in your life.

What should you do?

It's OK to work extra-hard for short periods of time. Sometimes a special project deserves extra attention or a co-workers' vacation means you have to put in more hours.

For the most part, however, it's up to you to protect yourself. Focus on efficiency and getting work done faster. It's also important to consider if you're working because you need to or because you feel pressure to be present.

Talk openly with your boss about work-life balance and make sure your employer respects your needs. If he or she doesn't, it may be time to move on, because your long-term health matters more than your short-term paycheck.

Only you know if you're working too hard, but there are signs to look for. If you dread going into work and stop enjoying a job you once loved, that's a pretty strong hint that you may be working too hard. If that happens, you must to decide if you need to take a vacation, work fewer hours, or find something else to do entirely.

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