Unused vacation days are a sign that workers aren’t striking a work-life balance and are at risk of burnout.

"Beyond the red mark on balance sheets, not taking time off hurts employee engagement and productivity, affects talent retention, and expedites burnout — all of which hurt a company's bottom line,” says report author Kate Dennis in a statement accompanying the study’s release.

The higher up in an organization somebody is, the more likely they are to not claim all of their vacation. While just over half of employees (53 percent) did not use all of their paid time off, 59 percent of managers and 67 percent of executives forgo vacation time that they have earned.

That executives and managers are forgoing more vacation is likely linked to the fact that they generally are given more vacation. Somebody with five weeks of PTO is probably more likely to leave some vacation on the table than a worker with only two weeks of vacation a year.

However, the survey shows a unique nexus of factors that prevent senior managers from taking time off.

Whereas only 26 percent of executives and 33 percent of employees say that they avoid vacation because they fear returning to a “mountain” of unaddressed work, 55 percent of top-level managers said that was a big reason they don’t take all of their vacation.

Similarly, 52 percent of senior managers say they worry that nobody can do their work while they’re away on vacation, compared to only 27 percent of employees and 34 percent of executives.

Far more senior managers said that they find it harder to take vacation as they move up in the organization, compared to 23 percent of workers and 38 percent of executives.