More than 425 million people will fly internationally in 1997, and it's a safe bet that of these, a fair number of travelers will suffer from the modern malady known as jet lag. One estimate says that more than 90 percent of long-distance travelers are stricken, taking as long as one day per time zone crossed to fully recover.
Within just the past two decades, it has become firmly established that cycles of sleeping and waking, body temperature and hormone production--among many others--are synchronized by light into clockwork tempos known as circadian ("about a day") rhythms. "When you fly across multiple time zones," says Al Lewy, professor of psychiatry at the Oregon Health Sciences University, "you knock all these light-influenced rhythms out of kilter."
In 1980, Lewy made the discovery that intense light stopped the production of melatonin, a hormone known to influence our sleep cycles. Such discoveries have led to therapies--from carefully scheduled bright-light treatments before traveling, to the use of welder's goggles to block out light upon arrival, to the now widely recognized use of melatonin tablets to reset the body's internal clock. In this article, author Ed Kiester explores the causes of jet lag and its potential "cures."