Spring break is here, and summer vacations are just around the bend. But while increasingly stressed-out U.S. workers say having paid time off is critical, many still don’t even take all that they’re allowed.

Only 48 percent of U.S. workers say they use all their vacation days, according to a new survey from Pew Research Center. Those who don’t take all their time off say it’s because they don’t need it, or they worry about falling behind at work or feel badly about co-workers carrying their load. A few even think vacation time hurts their chances for promotions or could cost them their job.

There is growing anxiety in the labor force with layoffs spreading, hiring slowing and organizations cutting perks and other costs. Last week, the job site Indeed said it was reducing headcount because it’s “simply too big for what lies ahead” — an excuse used by many companies to justify recent cutbacks. It’s no wonder that workers are exhausted.

“Throughout the pandemic, we saw a surge of people leaving their jobs because of burnout and stress,” said Christy Pruitt-Haynes, global head of talent and performance at NeuroLeadership Institute, a workplace consultant. “We have also seen a steady decline in employee engagement.” In other words, she said, “Vacation time is more important than ever.”

The rise of remote work has also contributed to people taking less time off, according to Paaras Parker, chief human resources officer at Paycor, which makes software to help manage workforces. Doctor appointments, for example, can now be done virtually or by popping out quickly from a home office, instead of using up an entire vacation day.

Still, Pruitt-Haynes said the biggest thing that keeps most Americans from taking an extended break is simply “fear.”

“U.S. employees have been conditioned to believe if you aren’t at work, you are lazy or at risk of being replaced,” she said. “We also have been taught that to get more you have to work more, and since we all want more, we tend to prioritize active work over other things in our life.”

Private-sector employees in the U.S. get an average of 15 vacation days after they’ve been working for five years, rising to 20 days after two decades on the job, according to the Bureau of Labor Statistics. Separate research has shown that Europeans, who typically get more vacation days than Americans, feel less guilty about taking them.

About 80 percent of all private-sector employees in the U.S. get paid vacation, according to government data. In the Pew survey, which included more than 5,900 U.S. workers, more people said paid time off was “extremely” important to them than those who said the same about employer-sponsored health insurance, retirement programs, or paid family or medical leave.

But even unlimited PTO may not ultimately lead to more vacation days, Pruitt-Haynes said. A more effective policy would be to institute a minimum number of days that employees are required to take off, she said.

“When a company actively demonstrates that they are interested in prioritizing true self care for their team members, which is about boundaries not just bubble baths, then employees quickly recognize that,” she said.