Service can be strenuous, but a 1998 study of military reservists found that men on active duty in the U.S. were less burnt out than comparably stressed men who stayed on the job. Simply getting out of the office provides some stress relief—and reservists get a sense of perspective and detachment from their everyday work.

How long does vacation relief last? One study found that a mere three days post-vacation, workers were already showing signs of stress; three weeks after returning to the job, burnout levels were the same as they were before the trip.

A study of 57 high-tech workers who traveled overseas for work found that even though a business trip brings its own pressures and strains, stress and burnout declined during the trip. Changing the environment and escaping the workday rut seemed to make the difference.

Older women pick vacations that are appropriate for their age; older men tend to choose trips that will allow them to act younger than they really are.

Why do the first few days of vacation seem so long and the rest so short? A study of vacationers at an Israeli Club Med suggests that the first days stretch on forever because the experience is completely new. After that, habits like dining at the same table or swimming every morning make time seem to accelerate.

Older people who organize their vacations around having a good time feel younger than their years. Those who plan trips in order to escape day-to-day life, however, feel their age.

Like life, spring break seems to be more poignant in retrospect. Students on spring trips to Europe and Florida initially said they'd had less fun and less stress than they anticipated—but four weeks after the vacation, rated the trip as being both better and more difficult than it really was. People focus on the highs and the lows and don't remember all the mundane moments.