Feeling tired? Stressed? Overworked? Overdue for some rest and relaxation?

You’re not alone.

Increasingly, Americans are taking an “all work and no play” approach to their careers. U.S. workers are on track to sacrifice more than 421 million vacation days in 2005, valued at about $54 billion in economic productivity. And the numbers continue to climb. Americans gave up 415 million vacation days in 2004, a 50 percent increase over 2003.

An estimated one-third to one-half of all full-time U.S. workers do not use all the vacation days allotted by their employer and have an average of three to eight days of unused vacation at the end of the year. Hours worked per capita have increased 20 percent since 1970.

“My experience is that many executives don’t take all of their vacation,” said Sue Twit, vice president of client services for Right Management Consultants’ Des Moines office. “Many times it’s a reflection of the company culture and what is acceptable for leaders at the top. We all live within that culture, and the top leaders really need to model the behavior that they want to see in those who report to them.”

A survey by the Society for Human Resource Management found that paid time off was the second-most-important job benefit for workers next to health insurance. So why do so many U.S. workers leave it unused? Another survey, this one by Expedia.com, found that 10 percent of respondents said they were too busy at work to take time off, 13 percent said they could get money back for unused vacation days and 12 percent said they didn’t schedule time off soon enough.

And when they do escape from the office for a few days, they may not be able to get away completely. Laptop computers, BlackBerry devices and voice mail have made it easier for people to stay connected to their work, and more difficult to get a break.

“I’m seeing more and more people who, with all the technology we have available, they are accessing e-mails and checking voice mails when they’re on vacation,” said Jan Burch, owner of Jan Burch & Associates and president of the Central Iowa chapter of the Society for Human Resource Management. “It’s not always a pure getaway approach.”

The United States is the only modern country without vacation time minimums that are mandated by law. Employers in European Union countries are required by law to give their workers four weeks paid vacation. Twit said Americans could learn from practices in other countries, but added that a significant increase in vacation for U.S. workers could affect the country’s famously high productivity rate.

But some professionals say employers are giving more attention to the vacation issue and encouraging employees to take that time as a way to rest and recharge, and in turn become even more productive. Burch and Twit agreed that good managers will ensure that their employees schedule vacation, and at an appropriate time so as not to interfere with other employees’ vacations or major projects. Some companies, to encourage employees to use vacation time, have put a limit on the number of unused vacation days that are eligible for payout.

“I think it’s going to become a retention issue with Generation X and Generation Y folks,” Twit said. “They’ve seen what happened to their parents who devoted so much time to their jobs. And they’ve witnessed those same people having positions eliminated, etc. So they have a different perspective about work.

“They want to enjoy their work, be developed by their employer and have a life outside of work. The top talent, the future leaders are within that group. So if a company wants to retain those top talents, it’s going to have to be possible to live those values as an employer.”

From 1992 to 2002, there was a 16 percent drop in the number of recent male college graduates who said they wanted to move up within their company. For women, there was a 21 percent decrease.

“The reason those people don’t want to advance is they don’t want to give up their life outside of work,” Twit said.