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" There are few things more incredible than flying across an entire country that is thousands of miles wide in a mere afternoon by sitting inside the carcass of an enormous metal bird that screams through the air at hundreds of miles an hour. But there are consequences to moving this fast, moving faster than time on the ground can keep up: jet lag.  It&amp;#039;s a bummer to be groggy after any long flight, but have you ever noticed that landing in New York will leave you feeling more wiped out than landing in San Fransisco? The east versus west divide all comes down to the way your brain sets its internal rhythm, according to researchers at the University of Maryland which just published a new study in the journal Chaos.  While all of our days are technically 24 hours long, our bodies&amp;#039; natural tendency is to establish a rhythm that&amp;#039;s a little longer, closer to 24.5 hours. Traveling west\u2014which adds time to your day\u2014just increases this natural surplus. Traveling east\u2014which robs hours from you\u2014doesn&amp;#039;t just reduce this surplus but actually reverses it. And when it comes to your brain&amp;#039;s timekeeping chemistry, the former is a lot easier to adjust for. On the one hand, this seems screamingly obvious; it&amp;#039;s just harder to deal with a shorter day because you may not have enough time to get everything done and are probably not appropriately tired at bed time. With a longer day, you can just control for the changes by taking your time and relaxing a little.  But even for its seemingly obvious conclusion, the study comes with data. Specifically that\u2014when using a mathematical model to predict how the brain&amp;#039;s chemistry reacts to changes in time zones\u2014west-to-east travel can add as much as several days to the amount of time it takes for things to even out. In the most extreme case, researchers found that a nine-time-zone trip took eight days completely recover from when going east to west, but 12 from west to east.  There is, however, one major caveat. The exact effects depend on the person. As Michelle Girvan\u2014an associate professor of physics at the University of Maryland&amp;#039;s Institute for Physical Science and Technology\u2014explained in a statement on the study:  Some people may have a natural circadian rhythm with a period of 24.5 hours, while others may have longer or shorter natural rhythms. Our model suggests that the difference between a person&amp;#039;s natural period and 24 hours controls how they experience jet lag. So ultimately, it all depends on the kind of person you are. So just relax, try to make the best of the situation, and just think about how much longer it would have taken if you had to drive.  Source: Chaos via Gizmodo "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/flight/a21832/jet-lag-study-headed-east/>