If you're always the last one to leave the office at night, read very carefully: Working more than eight hours a day can kill you. Here are the details:

  • Long hours are bad for your mental health. One study found that people who regularly logged 11-hour days increased their risk of depression by 250 percent. Constant stress and lack of sleep are major factors. But the researchers also say that spending all your time at the office creates conflict at home – and doesn’t give you the chance to unwind and de-stress.

  • Too much overtime is also hard on your heart. Research shows that you can stay healthy if you keep it to a 45-hour workweek. But putting in more time than that raises your risk of cardiovascular disease by 50 percent. An “all work and no play” approach also keeps you from getting enough exercise, which contributes to chronic stress, high blood pressure, and a crummy diet.

Do you still think you can’t get it all done in 40 hours? A Harvard Business School study found that account executives who limited themselves to 8-hour days – and always left on time – were rated higher by their customers. They also got better productivity ratings from their bosses. In fact, in one study, workers who really focused were able to get everything done they needed to. Bottom line: Putting in overtime won’t do your career – or your health – any favors.