A team of researchers from the Harvard and Stanford business schools suggest in a new study that perhaps the most effective thing companies can do to improve worker health is to adopt better management practices.

Specifically, employers need to stop stressing their employees out.

"We find that job insecurity increases the odds of reporting poor health by about 50 percent, high job demands raise the odds of having a physician-diagnosed illness by 35 percent, and long work hours increase mortality by almost 20 percent," concluded the study, which was authored by Joel Goh of Harvard and Jeffrey Pfeffer and Stefanos Zenios of Stanford.