Viagra can reduce jet lag symptoms by up to 50%.

A team of Argentine scientists made the discovery when running tests on hamsters. Interestingly, it only applies when travelling forward through time zones, or east on a plane. The reason for this is mainly the way mammals’ body clocks are regulated by light and dark. 

The scientists, from the National University of Quilmes, shifted the light-dark cycle of hamsters six hours forward and monitored the hamsters’ subsequent activity. Typically, the hamsters were more active during the light cycles, running in their hamster wheels, and stopped when the lights went out. 

When Viagra injections were used without any changes to the light cycles, the hamsters were no more or less active. When the light cycle was sped up, however, the hamsters were much quicker to adjust when given Viagra. 

Dr. Diego Golumbek, who led the research, said the drug seemed to work this way due to a molecule called cGMP. cGMP has a role in setting the body’s time clock, and has higher levels of activity during the day. The Viagra blocks an enzyme that breaks down cGMP, which lets higher levels build up, thereby reducing the time it takes to adjust to the change in light. 

It is not recommended to take Viagra for this purpose, however. Doing so is considered an off-label use. 

(Source)