Each cigarette you smoke reduces your life by at least seven minutes. You could find that frightening. Or you could use it to justify a habit that helps you get by from day to day.

Thanks to a new study by professors at the B-schools of Harvard and Stanford, you can now perform the same existential calculus about another life-threatening subject: workplace stress

Yes, it's true: These researchers have ciphered how much life you stand to lose from a stressful job. Specifically, the researchers--whose findings were summarized in Wednesday's Washington Post--divided their work on mortality and life expectancy into 18 different groups based on ethnicity, education, and gender.

They didn't stop there. They analyzed the data using several stressful workplace factors, including: no health insurance, unemployment and layoffs, shift work, long hours, job insecurity, low social support at work, high job demands, and low job control. Here's what they learned: 

  • Across all 18 groups, the researchers found the biggest drops in life expectancy among people who worked in positions where the threat of unemployment and layoffs loomed, as well as jobs that lacked health insurance coverage.
  • After those two "killer" workplace stressors, the biggest drops in life expectancy came from low job control. 
  • After low job control, there was a gender-based split: The fourth-biggest drop in life expectancy for women came from shift work; for men, the fourth-biggest drop came from job insecurity.

The researchers were Joel Goh (HBS), Jeffrey Pfeffer (Stanford GSB), and Stefanos Zenios (Stanford GSB). According to the abstract of their paper, which appeared in the journal HealthAffairs, their overall conclusion was that "10 to 38 percent of the difference in life expectancy across demographic groups can be explained by the different job conditions their members experience."

In other words, any way you slice it, you're taking time off your life if you have a stressful job. It's the sort of news that could make you want to reach for a cigarette, especially if you're still at your desk as you read it.