Baltimore, MD – A focus group study in Baltimore and a nationwide survey now confirms what many American workers already know: few people actually take advantage of their vacation days.

Project: Time Off, which brands itself as “a national movement to transform American attitudes and change behavior,” found that over 50 percent of the workforce left vacation days unused in 2015.

For every summer vacation taken, it seems as though there’s another one that’s put aside. Over 650 million long-distance trips are made in the U.S. every summer, but meanwhile, Project: Time Off maintains that 658 million days of vacation time went unused last year. Of those days, 222 million were simply lost without rollover or other benefits.

“A company’s success is all about the degree to which your employees are engaged and effective,” said Doug Walker, a manager at Insperity HR Solutions. “If they aren’t engaged because they are burnt out or they aren’t effective because they are burnt out, they need a break.”

The newest findings from Project: Time Out are part of a recurring trend. Past surveys suggest that 96% of adults agree that taking time off from work is important — yet 41% still don’t plan on using up all of their vacation days in any given year.

“When it comes to taking time off, Americans themselves can be the biggest barriers,” the study’s executive summary reads. About 40% of respondents feared coming back to the office with a mountain of work waiting for them after a vacation. Another 35% felt no one else at the office could do their job. Others said they couldn’t afford to take time off (33%) or wanted to show dedication to their jobs (28%).

Part of the focus study in Baltimore included a group of managers, directors, and vice presidents, who appeared to send mixed messages to their employees. Around 46% of bosses stay connected while they’re away, and one-third have never discussed the benefits of taking time off with their employees.

Walker emphasized that real, unplugged vacations are important for feeling refreshed. “It’s in stillness that life’s sediment settles and the murkiness becomes clear,” he said.