The tired, confused, grouchy state that is jet lag just got a little bit worse. Lance Kriegsfeld and his team from the University of California, Berkeley have found that repeated jet lag may have permanent effects on brain function and memory.
Jet lag occurs when our personal circadian rhythm (the internal clock that tells us when it’s time to eat and sleep) is out of sync with our environment. For example, right after you fly from London to Los Angeles you'd like to get up and have breakfast around midnight. Most people recover from jet lag in a few days. Kriegsfeld and his colleagues wondered if there were any hitherto unrecognized long term effects of jet lag.
To find out, the scientists subjected hamsters (creatures with stopwatch precise circadian rhythms) to six-hour time shifts twice a week for a month. This is the equivalent of flying back and forth from New York to Paris. During the last two weeks and again a month later, the hamsters were given memory and learning tests.
Not surprisingly, the hamsters did poorly while feeling the affects of jet lag. What was surprising was that the animals still showed cognitive impairment a month later. Even more chilling, the hamsters that had experienced prolonged jet lag had only half as many new neurons in their hippocampus (a region of the brain critical for long-term memory) as the control hamsters. This new data correlates with other health risks associated with jet lag, such as an increased incidence of diabetes, heart disease and cancer.The scientists don’t believe that an occasional flight could have long-term effects. Remember, the hamsters had been subjected to the equivalent of 8 long flights in one month. Kriegsfeld does suggest that people who must routinely shift their days and nights do their best to maintain their daily rhythms. For example, he suggested that when required to sleep during the day they used blackout curtains to darken the room.