A study that has well-traveled older business-mice trembling: Aged mice whose circadian rhythms were messed with in a manner similar to what happens when you're jet-lagged on a westward trip had higher death rates than their eastern-directed and nontraveling fellow mice. From The Economist:
- Researchers led by Gene Block and Alec Davidson of the University of Virginia noticed that, in an earlier experiment, a surprising number of elderly rats died when the daily cycle of light followed by darkness was altered so that the light came six hours earlier. To examine whether there really was a link they conducted a separate experiment using three groups of mice.
Each group contained nine young male mice and about 30 old male mice. The first group was placed on a normal daily cycle of 12 hours of light followed by 12 hours of darkness. The second had its 12 hours of light delayed by six hours once a week, replicating the jetlag experienced after travelling west. The third group had its 12 hours of light advanced by six hours once a week, mimicking eastbound travel. The experiment lasted for eight weeks.
As might be expected, the young mice in each of the three groups fared relatively well; just one died. Of the elderly rodents whose days and nights were unchanged, 17% died. But the number of deaths in the two groups whose day-and-night cycles had been tampered with was far higher. Among the â€westboundâ€ groupâ€”those whose light cycle was repeatedly delayedâ€”32% died. The death rate in the â€eastboundâ€ group, whose light cycle was brought forward, was 53%. The results are published in this week's issue of Current Biology.
What does this mean to you? Probably not much, unless you have a habit of carrying your elderly pet mouse on business trips. But I thought it was interesting.