Time waits for no man, particularly when you're rapidly crossing several time zones. Your body just can't keep up.
Most long-distance travelers are affected by jet lag, caused by a mismatch between the external clock and their internal clocks. They get to their destination and often feel like they've been run over by a truck. They can't sleep or they feel sleepy at odd times. Perceptual skills and cognitive ability drop. Concentration goes out the window.
As motivational speaker and humorist Linda Perret once said, "Jet lag is nature's way of making you look like your passport photo."
Jet lag is like the common cold: There are all sorts of remedies but no cures. Researchers are starting to learn more about our internal clocks by studying the neuroscience involved, and one day there may be a drug to control the effects. That day isn't now, although travelers can make the transition to another time easier by using nonpharmaceutical techniques. Travel professionals say if you do nothing to counteract jet lag, it usually takes about a day to recover for every hour you gain or lose.
This disruption of our circadian rhythms - the body's internal, roughly 24-hour clocks - can be dangerous. A British survey of more than 2,000 people, released this week, found a high incidence of "driver lag." People reported problems with their driving ability for several days after flying home. The study, sponsored by an insurance company, suggests the condition could be contributing to more than 60,000 driving incidents a year in British airport parking lots or on the drive home from the airport.
Roopak Manchanda, 34, knows all about jet lag. Not as a scientist, but as chief information officer of an international company based in Beltsville. He makes some flight attendants look like novices when it comes to transmeridian flights.
"It's almost like you're drunk," he says of jet lag. "There's an immense feeling of tiredness. It messes up your entire calendar."
The symptoms - including disorientation, malaise and even indigestion - are becoming worse as he gets older. That's par for the course, says Dr. Teodor Postolache, a psychiatrist and director of the University of Maryland School of Medicine's Mood and Anxiety Program. Research is inconclusive on whether frequent flying makes the body more immune to jet lag, but age has been shown to amplify its effects.
Manchanda flies regularly to his company's offices in Singapore, Indonesia and France. His wife is from Barcelona, so they visit Spain a couple of times a year. Every other year, they fly to his native India.
"It adds up," he says.
What works best for him is to get on his destination's time as quickly as possible. That means sleeping on the plane - and staying awake once he gets there. "It's hard, but a couple of coffees help."
Like a large number of travelers (estimates are as high as 90 percent), Manchanda says he adjusts better to the local time if he's flying east to west. The main reason, says Postolache, is that our master circadian clock has a period slightly longer than 24 hours, so it's easier to "phase delay" - travel west - than "phase advance," or travel east.
That has implications for everyone from business travelers to elite athletes. Researchers found, for instance, that an average of 1.24 more home runs were hit in major league baseball games by the home team when the visiting team had traveled eastward, according to Postolache, who is the editor of the recent issue on sports chronobiology of the journal Clinics of Sports Medicine.
Theories about causes
There are three prevailing views about what causes jet lag, says Postolache. "For now, none of these theories has adequate support to dismiss the others."
One is that there's a mismatch between when you sleep and when you should sleep, which throws things out of whack.
Another view is that external night doesn't correspond to internal, or biological, night. Simply catching up on sleep isn't enough. The traveler can adjust to local time more quickly using aids such as sunglasses, darkened hotel rooms and exposure to artificial or natural bright light.
More recent research proposes that we get jet-lagged because our various internal clocks, which govern everything from liver function to hormones, adjust to time shifts at different rates and therefore don't correspond with the master clock situated in a small structure of the brain called the suprachiasmatic nucleus.
Gene Block, a University of Virginia biologist, with colleagues at UVA and Leiden University Medical Center in the Netherlands, found that the brain's central biological clock has two sections that fall out of sync with each other during long flights. One part, which is connected by a nerve to the retina, can adjust quickly to the new light/dark schedule. The other may take several days to adjust.