SAN JOSE, Calif. - As the economy improves and international travel begins to soar, a familiar but unwelcome chronic condition is on the upswing: jet lag.

For a tourist, who may travel overseas only every few years, it might mean nothing more than yawning at the Great Wall. But globe-trotting business executives with back-to-back international trips across multiple time zones must juggle power meetings and deal-making with disrupted sleep patterns - and do it over and over again.

Along with elite mileage status come symptoms of foggy memories of important meetings, lost luggage and misplaced mobile phones.

These frequent fliers "are all becoming time zone-less people," said Tim Chang, a partner with Norwest Venture Partners in Palo Alto, Calif., who heads to the airport virtually every other week. "You are in China but you have to do your conference calls with the United States."

For a six-week stretch at the end of 2010, he travelled to China four times. "It’s like a weekly commute," he said.

"I am the new norm," Chang said. "Investors have to find deals all over the world, business development and sales executives have to go around the world. Most startups probably have an India and China development team."

All this time aloft can create surreal moments on the ground.

"You end up becoming more absent-minded in your personal life," said Tom Lattie, a general manager at San Jose-based Harmonic, a provider of video infrastructure who logs about 190,000 kilometres a year.

A few years ago, he was travelling as many as 200 days a year with back-to-back international trips. At one point, Lattie said, he became "almost narcoleptic," and caught himself dozing off while driving one afternoon.

"You begin to think you aren’t jet-lagged but you probably are and you don’t realize it," he said in a phone interview while waiting for a flight in Frankfurt during an 18-day business trip.

Matthew Cui, an executive in the semiconductor industry, doesn’t have time to let his body catch up with Taiwan’s time zone, 16 hours ahead of the West Coast. When he touched down in Taipei on Thursday morning, he faced a grueling day of meetings, beginning with breakfast and continuing all day and through a business dinner.

Every now and then "my brain action stops," he said. "It just goes blank. Sometimes it’s so hard to keep my eyes open. You feel like you are dozing off and then you are saying to yourself, ‘No, no, no!’ It lasts for maybe 10, 20 minutes."

No cure for the disorder is on the horizon. The Food and Drug Administration in the U.S. recently rejected the latest claims that a jet-lag antidote pill had been developed. In December, the agency said biopharmaceutical company Cephalon could not add jet lag to the list of conditions that its stay-awake drug Nuvigil treats.

Fact is, said Dr. Clete Kushida, a neurologist and director of Stanford University’s Center for Human Sleep Research, "There is no real substitute for a good night’s sleep."

So transoceanic travellers are left to their own wits as they battle the pressures of doing global business with confused body clocks.

There’s no way to know how often out-of-sync circadian rhythms have led to blown deals or exasperated CEOs yelling, "You agreed to what?" But jet lag can lead to misfires. For instance, police have been known to pull over drivers they suspect are drunk, only to find out they are battling jet lag after stepping off an international flight.

Chen Ran recalls attending a biology research meeting last year after flying to the United States from Beijing where he couldn’t comprehend most of what was being said. "I was completely off," the 23-year-old student said Wednesday after arriving at San Francisco International Airport for appointments at a number of universities, including Stanford.

Sleep deprivation combined with "circadian rhythm misalignment" is often associated with decreased attention, Kushida said. It can impair memory and cause "alterations in frontal-lobe executive function," he added.

To avoid boardroom blunders, companies like Lattie’s, which does not usually pay for pricey business and first-class seats, want their executives to get a good night’s sleep in a hotel before heading to meetings.

These global sojourners are disciplined travellers. Those who occupy the rarefied world of business- and first-class cabins - where life can be a party with flowing wine and cocktails - live more like monks than jet-setters. Many don’t touch alcoholic drinks - if they do, it’s to sip just one beer or glass of wine - and are more concerned with finding quiet time to work and sleep than nibbling on foie gras.

"When was the last time you had 12 hours of uninterrupted time to read, eat and sleep?" Chang said.

Cui said proper diet helps him feel at home in the air. Taiwanese carrier EVA AIR serves a traditional Asia breakfast that he says helps him stay balanced.

"You get all that shredded pork, you have some vegetables, you have some eggs and some mushrooms," he said.

Global commuters become experts at sleep management.

Sleep "is like a bank account," said Ta-lin Hsu, founder and chairman of H&Q Asia Pacific in Palo Alto. "You can never get as much as you need."

The trick is staying up as late as possible after arriving, Lattie said.

It’s also important to learn to take quick naps in airports and taxis.

But, he added, "Going back to your room in the afternoon and laying down on the bed is deadly. I lay down at 4 p.m. and wake up at eight and I don’t know where I am. It all goes sideways."

Even when these residents of the clouds do all they can to alleviate the travails of jet lag, they can’t avoid feeling a bit off-kilter.

"It’s almost like the plane is your apartment," Chang said. "You get into your apartment and you land in some strange city. Then you go back to your apartment and go to some other strange city."