If you're a regular reader of this column, you'll know I've covered study after study showing that consistently working long hours is counterproductive. Whether you look at classic economics research, anthropology, neuroscience, or simple common sense, the same picture emerges. The quality of people's work dips dramatically after 40 hours a week, which makes super long workweeks inefficient. A new study finds they are also deadly.  

The new data from the World Health Organization shows that 745,000 people died in 2016 from working long hours, and that number is up 29 percent since 2000. Workweeks of 55 hours or more were particularly harmful. And though more recent data isn't yet available, the researchers feel lockdowns and remote work may have only increased the dangers of super long workweeks. 

"The research found that working 55 hours or more a week was associated with a 35 percent higher risk of stroke and a 17 percent higher risk of dying from heart disease, compared with a working week of 35 to 40 hours," reports the BBC. Forty-five percent of those who died were men middle-aged or older, and about 9 percent of workers globally put in 55 hours a week or more. 

So how do long hours kill? The researchers suggest a handful of different mechanisms. 

Chronic stress 

Living with stress long-term can wreak havoc on the body. All that adrenaline and cortisol continually coursing through your veins puts you at higher risk of depression, heart disease, weight gain, and sleep problems, among other conditions, according to the Mayo Clinic.

Perhaps it's not so surprising then that long workweeks caused your chance of having a stroke to spike. Women who worked excessive hours were also more likely to be depressed, according to the new study.  

No time for healthy habits

Super long workweeks don't just actively harm your body, they also prevent you from doing the sort of things, like exercise, getting adequate sleep, and cooking healthy meals, that might counteract all the ill effects of stress. 

Unhealthy coping mechanisms 

Finally, working brutal hours leaves people more vulnerable to choosing unhealthy ways of coping with their stress and exhaustion, such as excess alcohol or smoking. 

Entrepreneurs may need to sometimes put in crazy hours to get through a crunch period. No one is suggesting that will cause you to keel over immediately. But this research makes it crystal clear that keeping up a punishing work schedule over years or decades has dire health consequences. 

It's also a bad policy to drive your team to put in long hours, and not just because you should probably feel bad about contributing to your employees' early demise. As science journalist Robert Roy Britt reminds bosses in his write-up of this study, pushing people to their breaking point is also simply bad business. 

"Research has shown that long hours don't translate into greater productivity, and instead can actually be bad for employee health, causing higher absenteeism, more turnover, and rising insurance costs. The bottom line, in case you're sharing this story with your boss: Working too many hours is bad for you and bad for your company's bottom line," he concludes. Amen to that.