Doing Stupid Things in Jet Lag? A Study Suggests Why

In addition to making you groggy and dazed, jet lag may make you stupid. A study presented November 15 at the annual Society for Neuroscience meeting finds that hamsters suffering extreme, chronic jet lag had about half the normal rate of new neuron birth in a part of the brain.

The experiment shifted the animals' light-dark schedules to simulate the repeated time-zone crossings of, say, a flight attendant or a traveling executive. The hamsters' brains — specifically the hippocampus, the region involved in memory — produced new neurons at roughly half the normal rate. New neuron birth in the adult brain is associated with learning and memory, so the finding suggests a mechanism for the well-known mental fog of the long-haul traveler.

Caveats apply, as they always do when the subjects are hamsters. The jet lag imposed in the study was extreme and chronic — far beyond what a traveler experiences on a single trip — and the leap from rodent neurogenesis to human cognitive performance is long. Still, the finding is a striking addition to the evidence that circadian disruption is not just a matter of feeling tired. Your body's clocks are tangled up with memory, learning, and mood in ways researchers are only beginning to map.

For the frequent flyer, the takeaways remain the boringly practical ones: light exposure, consistent schedules, and sleep hygiene beat any gadget. The hamsters, one suspects, would agree — if they could remember what they were supposed to say.