That refrain is one workers may start hearing more and more from their employers. And it's not out of concern for the bags under their employees' eyes. It's because of worries about the companies' own bottom lines.

Hewlett-Packard Inc. and Sun Microsystems, for instance, were among Silicon Valley stalwarts that sought to send staff home for an extended Fourth of July holiday in a bid to save money while waiting for the economy to improve.

And companies including Charles Schwab, Motorola and Bridgestone in recent months have also pressured employees to days off to control costs. Many of the companies employing these tactics had earlier taken the cost-cutting move of laying off workers.

Schwab, for instance, encouraged noncustomer service employees to take off three designated Fridays earlier this year as either paid or unpaid vacation. Motorola gave employees until June 30 to take an average of two weeks mandatory paid or unpaid vacation.

In Sun's case, the firm later had to back off its mandatory vacation policy after it was warned that California state law may prohibit employers from forcing salaried employees who don't get overtime to use vacation hours if they're ready and able to work. Even so, California would be the exception to the rule, says experts.

Most companies are well within their rights in forcing workers to take vacation time, says Larry Lorber, an attorney with Proskauer Rose LLP in Washington. And despite the potential for eroding employee morale, Lober added that salaried employees should get used to the idea of their companies closing the office on a whim and requiring them to use vacation days if they want to get paid.

"Companies are bringing the forced shutdowns common in manufacturing into the white-collar workplace," he says. The trend is being driven by an economic slowdown that sometimes makes it unnecessary for companies to keep producing products that fewer are buying.

In addition, says Lorber, corporate bean counters increasingly are zeroing in on accrued vacation time with an eye toward minimizing the exposure to a big payout when the employee leaves the company. Companies do this by forcing employees to use vacation time in the year it was accrued or lose it — no more carrying forward unused days into the next year.