his summer, you might have noticed a business traveler at airport security slipping a watch - or what appeared to be a watch - off his or her wrist and placing it into the plastic dish. If so, you might have noticed that it was not a real timepiece but a gizmo of the sort Dick Tracy might wear.

The traveler would have been wearing this unlikely fashion accessory because he was participating in an unusual study that sought to determine what caused business travelers to tire, lowering their away-game performance.

In addition to donning the actigraph - a black watchlike device that monitors the wearer's movements - the 25 volunteers kept logs of their daily activities and sleep quality and tested their reaction times on a hand-held computer. This may sound like "The Right Stuff" - and the study was, in fact, run by a former NASA scientist - but it was for a good cause: improving the productivity of business travelers.

The results are in and some are a bit surprising.

The study was led by Alertness Solutions, a consulting firm in Cupertino, Calif., that advises companies on sleep issues, and was sponsored by Hilton Hotels, Suites and Resorts, which wants to use the results to figure out what new services and goodies to offer guests to make them fresher and more alert.

Mark R. Rosekind, president and chief scientist of Alertness Solutions, says that unlike most similar studies, which are aimed at making travel safer, this one looks at how exhaustion affects people's performance on the road. He says he became interested in analyzing slumber as a Stanford undergraduate when he took the sleep and dreams course taught for 33 years by the sleep expert William Dement.

At first Dr. Rosekind did academic work, becoming director of Stanford's Center for Human Sleep Research. Then he went to NASA, where for seven years he ran the Fatigue Countermeasures Program. After a while he realized his findings could be applied to business, and he started Alertness Solutions.

Some reasons for fatigue on business trips are obvious. People tend to eat and drink more and exercise and sleep less.

"You get back to that hotel room and it's so easy to sit there and order room service and watch TV," said Mark McCleary, a senior consultant with the software company CorVu in Minneapolis, who volunteered for the test. "And room service is fatty appetizers and fatty entrees. You can't order chicken breast with steamed vegetables anywhere. At home, I might be mowing the lawn or taking a walk."

Mr. McCleary figured that he was an ideal candidate to be scrutinized. He is on the road two to three weeks a month and often feels drained.

"I've probably had near misses in car accidents,'' he said. "I can't remember how many times I've gone back to the hotel and can't remember my room number. I'm probably not as productive for clients and I'm billing by the hour. Productivity is important to me and to my clients."

The experiment sought out travelers going across at least two time zones for a business trip two to four days in duration. "Two time zones gives you some kind of body-clock disruption and being on two to four days is long enough for it to have some disruption to affect you," Dr. Rosekind said.

The actigraph has an electric sensor that acts like a mercury switch, recording a movement every time the wearer shifts position; it also measures sleep quantity and quality. "At NASA, I'd use electrodes," Dr. Rosekind said. "What's neat about this is you can wear it on your wrist and it gives us objective measures of the 24-hour pattern of when you're asleep and awake."

The three-times-a-day reaction-time test - or rather, the Walter Reed Army Institute of Research Psychomotor Vigilance Test - required users to press a button on a personal digital assistant whenever the image of a bull's-eye appears on the screen; response speed is measured in milliseconds, providing a measure of alertness.

One volunteer, Jennifer Sipala, a consultant for the Army at the Picatinny Arsenal in New Jersey, said she was surprised at how much lower her average score on the bull's-eye test was on her travel days compared with the two (presumably more relaxed) days before the trip.

This New York-based reporter, having worn the actigraph and taken the test on a trip to Los Angeles, can confirm that the more tired you are, the slower you push that little button - no matter how much your inner coach is goading you to move faster.

In addition to wearing the actigraph and doing the tests, the volunteers kept logs of their activities. At night, they jotted down information about their day, like when and what they had eaten, how much or how little they had exercised, whether they had taken a nap, how much alcohol or caffeine they had imbibed, how stressed they had felt and how alert and productive they had been.

In the morning they described their sleep patterns - how long it had taken to nod off, how well and how long they had slept, how often they had woken up and how they had felt on getting up.

So what did the study find?

First, business travelers think they perform better and sleep more than they actually do. While the volunteers ranked themselves as highly or extremely productive, their performance dropped by almost 20 percent while traveling. They also reported getting an hour more sleep than they actually did.

Surprisingly it was the night before the trip that they got the least sleep - five hours on average. What that means, Dr. Rosekind said, is that they started the trip practically primed to be unproductive. "They were miserable from sleep loss even before they left," he said. To compensate, Dr. Rosekind says, even a 10-minute snooze at the hotel before a dinner meeting will help. And because caffeine takes a while to kick in, the two can be combined by drinking coffee or tea before the nap. To keep alert at business discussions, he recommends letting as much light into the meeting room as possible, talking a lot and keeping active, if only by taking notes.

The study found that exercise was the most effective means of increasing performance, with those who exercised performing 61 percent better than the nonexercisers on reaction and alertness tests. It also found that travelers performed best in the afternoon, not in the morning, as many might suppose.

Dr. Rosekind suggests that if you are going on a two- or three-day trip from one coast to the other, you should plan meetings according to your home time because you will not be there long enough for your internal clock to adjust.

Robert E. Dirks, senior vice president for brand management and marketing at Hilton Hotels, said the company would use the findings to develop new products and services that would be announced in January. He declined to give specifics except to say that they would be designed "to reduce stress and anxiety and make road warriors more productive.''

Dr. Rosekind says the study will also help his work. He already has a handful of other projects focusing on productivity rather than safety. "I'm really hoping other folks wake up," he said, "and see the safety side is an issue but there is also a performance issue."

Readers are invited to send stories about business travel experiences to businesstravel@nytimes.com.