The erectile dysfunction drug sildenafil might help recovery from jet lag after eastbound flights and prevent health problems from shift work, according to animal studies by researchers in Argentina (Agostino PV et al. Proc Natl Acad Sci U S A. doi:10.1073/pnas.0703388104 [published online May 22, 2007]).
Sildenafil interferes with cyclic guanine monophosphate, a molecule involved in a signaling pathway that helps regulate the body's circadian rhythm. When the researchers injected hamsters with the drug and woke them up 6 hours earlier than normal by switching on bright lights, the animals adjusted 25% to 50% more quickly than did controls. However, the drug did not achieve the reverse effect when the scientists delayed turning on bright lights to simulate westbound travel.
Stephenson J. Jet Lag Relief?. JAMA. 2007;297(23):2578. doi:10.1001/jama.297.23.2578-d