It's no secret that long-distance, west-to-east air travel Seattle to Paris, for example can raise havoc with a person's sleep and waking patterns, and that the effects are substantially less pronounced when traveling in the opposite direction.
Now researchers, including a University of Washington biologist, have found hints that differing molecular processes in an area of the brain known as the suprachiasmatic nucleus might play a significant role in those jet lag differences.
Human circadian clocks operate on a period about 20 minutes longer than one day and so must be synchronized to the light-dark cycle of the solar day, delaying or advancing their time in response to light.
Someone whose clock runs faster than a solar day must delay it on a daily basis, and someone whose clock runs slower than a solar day must advance it. These daily adjustments happen naturally, and without our noticing, but the process is disrupted by sudden large shifts in the light-dark cycle because of a radically new geographic location.
Researchers previously learned that delaying the circadian clock happens through different pathways in the suprachiasmatic nucleus than advancing the clock does. The new research shows that, at a molecular level, the mechanisms responsible for resetting the expression of the "clock genes" are drastically different.
"We have known for decades that, in humans and other organisms, advances are always much harder to achieve than delays. For example, compare jet lag going to Europe with that coming back," said Horacio de la Iglesia, a UW associate professor of biology.
"One of the reasons may be that these two forms of resetting the clock involve different molecular mechanisms at the clock level," he said.
de la Iglesia and William Schwartz of the University of Massachusetts Medical School are corresponding authors of a paper detailing the research, published online recently (Oct. 3)
|Contact: Vince Stricherz|
University of Washington