14 DAY TRIAL // A new scientific study conducted on rats proved that jet lag most likely occurred when two groups of neurons in the brain were thrown out-of-sync, in that they no longer worked together. Regularly, the ventral and dorsal neuron groups in the suprachiasmatic nucleus, at the base of the brain, cooperate in assessing the right time for sleep, but, in the case of long flights over many time-zones, discrepancies may appear between them, as each processes the information they receive differently.
The team of experts at the University of Washington in Seattle (UWS) that conducted the experiments also said that the circadian rhythm, which is the human body's internal clock, or time-keeping system, was, to some extent, influenced by the light-dark succession, as in by the flow of days and night. Traveling extensive distances or working until late at night can cause imbalances in this rhythm, and they can throw the entire body off-balance, with implications for everything, from muscles to the brain and the mood.
In their study on innocent rats, the experts found that the ventral (bottom) neuron group in the suprachiasmatic nucleus (a brain region located below the hypothalamus) was responsible for detecting periods of light and darkness throughout the day. It receives its information directly from the eyes and processes it directly. Previous studies have shown that these neurons also play an important role in the part of sleep caused by physical fatigue, when people slumber soundly at night after a hard day's work.
The dorsal (top) neuron group is not involved in such assessments of night and day, or light and darkness. It plays a predominant role in the rapid-eye movement (REM) segment of sleep, which is when people dream. Now, usually, the dorsal and ventral groups work together, but extensive and long travel can throw them off-balance and make each believe that the other one is doing something wrong.
“We found that after exposing rats to a shift in the light-dark timing that simulates a trip from Paris to New York, REM sleep needed 6 to 8 days to catch up with non-REM, or deep, sleep, the sleep you usually experience in the first part of the night. It could also explain why jet lag is associated with lower learning performance. We think the disruption of the normal circadian sequence of sleep states is very detrimental to learning,” LiveScience quotes Horacio de la Iglesia as saying. He is the co-author of a new study detailing the find, published online in the April 16th issue of the journal Current Biology.