A chemical affecting cells in the biological clock could help people adjust more quickly to abrupt shifts in daily light/dark schedules, U.S. scientists say. Researchers at Washington University in St. Louis report a small molecule called VIP, for vasoactive intestinal polypeptide, known to synchronize time-keeping neurons in the brain's biological clock, has the startling effect of desynchronizing them at higher dosages. Far from being catastrophic, the temporary loss of synchronization actually might be useful, they suggested. The desynchronized neurons are better able to re-synchronize to abrupt shifts in the light-dark cycle such as those that create jet lag or make shift work difficult, they said. Writing in the journal Proceedings of the National Academy of Sciences, the scientists report neurons knocked for a loop by high levels of VIP need only half as long as undisturbed cells to adapt to a new schedule. Finding a way to coax the brain into releasing its own stores of VIP could deliberately cause desynchronizing so the body's clock will reset to a new time, they suggested. While the biological clock has evolved to be able to adjust to slow seasonal changes in light/dark schedules, abrupt changes found in the fabric of modern life can be difficult to deal with, the researchers said. "We were curious to see whether adding extra VIP would improve the ability of biological clocks to make big adjustments," study leader Eric Herzog said. "We found that in mice we could cut 'jet lag' in half by giving them a shot of VIP the day before we 'flew them to a new time zone' by shifting their light schedule," he said. The study is the first demonstration that increasing a chemical the brain already makes could improve the adaptability of the biological clock, the researchers said. "We're taking the system the brain uses to entrain to changes in the seasons and goosing it a bit so that it can adjust to bigger shifts in the light schedule," Herzog said. "We're hoping we'll be able to find a way to coax the brain into releasing its own stores of VIP or a light trigger or other signal that mimics the effects of VIP."