Which part of your vacation brings you the most happiness? Lying on the beach? Breakfast poolside? Skimming across the ocean on a rented jet ski? How about: surfing the web for flights and hotels.

While planning a trip may not sound like that much fun, a new study in the journal Applied Research in Quality of Life finds that it s before a vacation, not after, when travelers reap their biggest boosts in happiness.

How could we be happier before a vacation than after? Why do the effects of a vacation wear off so quickly? And what does all this tell us about how best to allocate our vacation days and dollars?

It should be noted upfront that happiness research is, at best, an imprecise science. Measures of happiness are, of necessity, indirect. There s no chemical in the blood to analyze; and a direct survey question (e.g., How happy are you on a scale of 1-10? ) is likely to bump up against the limits of people s self-knowledge. What s more, cross-cultural differences in how people conceive of the very idea of happiness can make it difficult to compare the wellbeing of, say, a 53-year-old Japanese housewife and a 26-year-old Williamsburg hipster.

Nonetheless, within relatively homogenous samples, certain findings are consistent. Money, after one is free form heavy debt or constant material depravation, does little to boost happiness. Likewise, the acquisition of new material possessions offers little sustained benefit, as we quickly get used to new things. Relatedly, it s less the absolute amount of stuff we have that makes us happy than it is the feeling that we re keeping up with (or doing a little better than) the Joneses.

It s against the backdrop of these findings that a Dutch research team looked specifically at the effect of vacations on happiness. Previous studies had found that vacations have little to no effect on happiness. Could there really be so little effect? After all, billions of people spend trillions of dollars on vacations every year. Is that all spent on happiness that dries up as soon as the plane s wheels touch back down on home soil? Does the length of a vacation matter? How about how relaxing a vacation is?

Using a sample of 1,530 Dutch speakers from the Netherlands, 974 of whom took a vacation (vacationers) and 556 of whom did not take a vacation (non-vacationers) during a 32-week period in 2006, the researchers compared the happiness of the two groups at varying time periods before and after they went on holiday.

Using a measure of happiness where respondents were asked whether they had recently enjoyed their daily tasks and whether they had recently felt unhappy or gloomy and dejected, the researchers found, as in previous studies, little difference post-trip between vacationers and non-vacationers.

Only the group of vacationers who rated their trip very relaxing experienced a significant boost in happiness peaking for two weeks after they got back and then completely fading out by two months after returning home.

Now, while two weeks of a decent happiness boost and a perceptible buzz for two months is nothing to sneeze at, only a small subset of people found their trips very relaxing. Some found their trips actually to be stressful, and the majority of people, who reported their vacations as merely relaxing (as opposed to very relaxing), were virtually indistinguishable from those who had taken no vacation at all.

Where a real happiness gap showed up, however, was in the relative happiness levels of vacationers and non-vacationers in the weeks leading up to trips the time period when we actually do most of the spending, perhaps not coincidentally for periods as long as eight weeks.

The reasons happiness after a trip might be small or short-lived fit in well with what we know about happiness. We adjust quickly to new things after purchasing them even the relaxation and memories we buy when we take a vacation. Even our tendency toward comparison might be involved: Before a vacation, we re better off than our non-vacationing peers; afterward, we re back in the same boat as everyone else. And, intuitively, we all know the letdown of going back to the grind after a week in a place with palm trees instead of paperwork.

Why, exactly, we re happier pretrip is less clear and the study s design doesn t give us much insight beyond showing us that the bump exists. But it makes some sense when one reflects on it. Merely imagining a pleasurable experience is pleasurable, and that s what we do when we plan a vacation. Also, before a vacation, we haven t experienced any of the stress; we haven t waited in line at airport security, we haven t gotten sick from drinking the water, we haven t fought with our kids or significant other.

The practical lesson seems pretty clear: Take more, shorter vacations. And this squares up with another finding of the Dutch study: that the length of a vacation doesn t seem to affect how much happiness we take home with us.

If anticipation gives us pleasure, we can maximize anticipation. In a very real sense, after all, the anticipation is the vacation.

Ryan Sager writes the blog Neuroworld at TrueSlant.com.