With Memorial Day and the summer vacation season fast approaching, it’s important to remember one of my Business of Management truisms: Sometimes workers need to get away from work.

Yes, there is a constant drumbeat to improve productivity, but treating employees like overtaxed mules isn’t the way to do it. Smart managers know that everyone needs a break and that you actually increase productivity when workers get time off to relax, reflect and recharge their batteries.

Unfortunately, that’s not the trend today. CareerBuilder released its annual vacation survey this week, and its shows that 25 percent of all workers plan to stay in touch with work while on vacation, up from 20 percent last year. The survey also found that nearly 10 percent of workers were expected to be checking e-mail, voice mail and staying in touch with the office while on vacation, and that 15 percent of workers gave up vacation days last year because they didn’t have time to take them.

“Taking a vacation is a great way for workers to re-energize themselves and bring fresh ideas back to the table,” said Rosemary Haefner, vice president of human resources at CareerBuilder.com. “Unfortunately for some workers, getting away can add unnecessary stress to their lives. Twelve percent of workers said they feel guilty when they are on vacation, and 6 percent felt that it could lead to them losing their jobs.”

Getting workers to take a vacation can be more difficult than it seems. Sometimes, a manager needs to insist that people get out of the office and take time off, although smart managers would do well to avoid how Chrysler’s Bob Nardelli does it. A better model would be to follow what IBM does—let workers take vacation whenever they want for as long as they want, just as long as they get their work done.

This is all part of a more flexible workplace, the kind we all need to be fostering if we want to get the most out of those who work with us and for us. As I’ve said before, the modern workplace demands a modern approach to management. Giving workers more flexibility not only keeps productivity high, but it also helps retain talent and keep people happy. More important, it treats them like adults.

I’m sure there are some who will look at the CareerBuilder vacation survey and simply see it as confirmation that some workers simply care about their jobs so much that they want to keep in touch even when they are away on vacation. That certainly may be true, but in my mind, good managers work with staff to let them know that they can let go when they are off and that no one will be worse off for it.

This shouldn’t be a surprise, but I am one of those people who can’t let go when they are on vacation. I’m the guy who always checks his e-mail. Funny thing, though: I find I come back a lot more refreshed and rejuvenated the more deeply I can withdraw and get away from the office. The times I have managed to completely get away with little or no contact, the better I feel—and perform—when I return.

In my book, helping your staff stay refreshed and rejuvenated is just as important as anything else you do. With summer vacation season upon us, now would be a good time to give that approach a try.