A friend recently told me about an automatic email reply she had received from a colleague. It began innocuously enough—“I will be out of the office next Monday and Tuesday"—but it grew more alarming as it went on. “Because I have accumulated too many days of paid vacation," it said, "I have scheduled a trip to Chicago for the weekend in order to use some of them.” (I’ve changed some details here to protect identities.)

As an anecdote, this autoreply stands as a tidy illustration of one man’s work ethic. When stretched, it might color a picture of what the work culture at my friend’s company is like.

That’s why I was surprised to read a report this week that suggested that an indifference to—or perhaps even fear of—taking vacation isn't just limited to that one employee at that one company. According to the report, put out by the U.S. Travel Association, four in 10 American workers allow some of their paid vacation days to go unused and expire—even though 96 percent of workers claim to see the virtue in taking time off. Another report, from 2013, found that workers were letting an average of 3.2 vacation days expire, unused.

How Much Paid Leave Do Employees Say They'll Take This Year?

U.S. Travel Association

It should be noted that the U.S. Travel Association is an industry group, and as such, it has a vested interest in making sure people continue to take time off and travel around the country. In fact, “Vacation” conspicuously sits atop the report’s list of what workers tend to use paid leave for. For that reason, perhaps some of the report’s findings—that, for example, “two-thirds of workers are receiving negative, mixed, or no messages about taking PTO from their company”—should be taken with a grain of salt.