In this Monday, June 19, 2017, photo, a person types on a laptop keyboard, in North Andover, Mass. The American workplace is grueling, stressful and surprisingly hostile. So finds an in-depth study of 3,066 U.S. workers, released Monday, Aug. 14, 2017, by the Rand Corp., Harvard Medical School and the University of California, Los Angeles. (AP Photo/Elise Amendola)

WASHINGTON — The American workplace is grueling, stressful and surprisingly hostile.

So concludes an in-depth study of 3,066 U.S. workers by the Rand Corp., Harvard Medical School and the University of California, Los Angeles. Among the findings:

Nearly one in five workers — a share the study calls “disturbingly high” — say they face a hostile or threatening environment at work, which can include sexual harassment and bullying. Workers who have to face customers endure a disproportionate share of abuse

Nearly 55 percent say they face “unpleasant and potentially hazardous” conditions

Nearly three quarters say they spend at least a fourth of their time on the job in “intense or repetitive physical” labor. “I was surprised at how physically demanding jobs were,” says lead author Nicole Maestas, a Harvard Medical School economist

Telecommuting is rare: 78 percent say they are required to be present in their workplace during working hours

Only 38 percent say their jobs offer good prospects for advancement. And the older they get, the less optimistic they become

About half say they work on their own time to meet the demands of their job.

“Wow — (work) is a pretty taxing place for many people,” Maestas says. “I was surprised by how pressured and hectic the workplace is.”

In many cases, less-educated workers endure tougher working conditions. For example, fewer than half of men without college degrees can take a break whenever they want to, compared to more than 76 percent of men with college degrees. Likewise, nearly 68 percent of men without degrees spend at least a fourth of their time moving heavy loads.