A recent story in Science News describes a serious case of the stupids inflicted on Syrian hamsters by UC Berkeley researchers studying the effects of jet lag on brain function. (Obviously, the intent here was to find out what jet lag does to people.)
Advancing the hamsters' sleep/wake cycles by six hours - the equivalent of a flight from New York to Paris - every three days for almost a month caused a serious slowdown in the rate at which new neurons (nerve cells) formed in the hamsters' hippocampus, a part of the brain plays a key role in memory and learning.
What's more, the hamsters' capacity for locating their running wheel was considerably impaired by the jet-lag routine (and everybody knows you don't get between a hamster and its running wheel). Even a month of rest and recuperation left the animals measurably dumber than normal. That's saying a mouthful.
Now, there are some caveats to the study: First of all, no equivalent six-hour "flights" in the westward direction (that is, six-hour clock setbacks) were inflicted upon the experimental rodents. So there's no telling whether a trip to Hawaii would have refreshed their memories instead of eroding them.
In the second place, these animals didn't really get to land in France. Who can gainsay the neuron-numbing effect of learning you've just lost six hours of sleep and you're still still stuck with the same old cheese?
Third (and you knew this), hamsters are not humans. Speaking for myself, the very prospect of a six-hour eastbound flight to a business appointment is enough to squirt half of my hippocampus out of my left ear. On the other hand, the anticipation of ditching the brain-abrasive up-at-six-a.m.-and-don't-forget-to-take-the-compost-down routine for a week or two of cerebro-stim a la les impressionistes de le Musee d'Orsay would seem to make an eastward journey a flight to remember, not forget.