Travellers flying across the Atlantic could beat jet lag by taking Viagra, research on hamsters has suggested.

Scientists have discovered that the impotence drug helped the animals to cope when their body clocks were disrupted in a similar fashion to jet lag.

The beneficial effect, however, was seen only when a time change like that of a long eastbound flight was simulated. This indicates that Viagra might be helpful to travellers flying from New York to London, but not to those going in the opposite direction. In a study led by Patricia Agostino, of Quilmes National University in Buenos Aires, scientists simulated the effects of jet lag in hamsters by switching on lights six hours earlier than usual. The animals were then monitored to determine how quickly they adjusted to the new timing of their days, by noting how soon they began running in their exercise wheels.

One group of hamsters was injected with a very low dose of Viagra, also known as sildenafil, on the night before the induced time change. These animals recovered from jet lag between 25 and 50 per cent more quickly than those that did not receive an injection.

The effects did not apply when the effects of a time-zone change in the opposite direction were mimicked.

Though Viagra was developed as a treatment for hyper-tension and angina, it was found to be more useful for treating erectile dysfunction. It achieves this effect by dilating blood vessels, improving blood flow to the genitals.

Dr Agostino’s team sought to investigate Viagra’s effects on the body clock as the drug is also known to interfere with the action of a naturally occurring compound called cyclic guanine monophosphate (cGMP), which plays an important role in regulating circadian rhythms – the body clock.

The findings are preliminary and the study would have to be repeated on human beings before Viagra could be recommended for treating jet lag or other body-clock disruptions. But it could also be taken by shift workers, or those suffering from certain sleep disorders.

“Shift work and chronic jet lag reduce mental acuity and increase the risk of a number of medical problems,” Dr Agostino said. “A potential jet-lag treatment for advancing cycles could also be important for the safety of counter-clockwise rotating shift work and the potential long-term health consequences for airline crews regularly crossing time zones.”

The dose used in the experiments is lower than that used to treat impotence. This may reduce side-effects such as heart problems and eye disorders.

Jet lag occurs because the body’s natural clock is set according to the patterns of daylight and darkness that it is used to, and it takes a while to adjust to a new time zone.

While many remedies are available, there is limited evidence that any are particularly effective. Some research suggests benefits from taking the hormone melatonin, but multiple doses are needed to get an effect, compared with only one dose of Viagra in this study.

Details of the research are published in the journal Proceedings of the National Academy of Sciences.

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