Jet lag is a pain. Besides the inconvenience and frustration of traveling more than a few time zones, jet lag likely causes billions of dollars in economic losses. The most effective treatment, according to much research, is structured exposure to light, although the drug melatonin may also sometimes be helpful at bedtime.

Both approaches have been used for more than 20 years, and during that time no viable new interventions have appeared.

Recently, however, research into the molecular biology of circadian rhythms has raised the prospect of developing new drugs that might produce better results.

Jet lag occurs when the “biological clock” in the brain becomes misaligned with the local rhythm of daily activity. The ultimate goal of circadian medicine is a treatment that instantly resets the brain's clock. Failing that, it would be helpful to have treatments that speed the rate of adjustment. Four recent discoveries suggest new possibilities.

The first involves vasopressin, which is the main chemical signal used to synchronize cellular rhythms of activity in the brain area that is responsible for our biological clock. Blocking vasopressin makes it much easier to reset this clock. Potentially, a drug that interferes with vasopressin could work as a fast-acting treatment for jet lag.

The second and third possibilities involve a pair of brain chemicals called salt-inducible kinase 1 (SIK1) and casein kinase 1ε (CK1ε), both of which limit the ability of light to reset the brain's clock. Drugs already exist that interfere with their action and greatly increase the effectiveness of light exposure. The existing drugs are not viable jet-lag treatments, because they are hard to administer and have unpleasant side effects, but researchers hope better drugs can be developed that work in a similar way.

The strongest possibility in the near term involves the neurotransmitter serotonin. In addition to its well-known roles in mood and motivation, serotonin operates inside the brain's clock. Evidence from small studies suggests that several drugs that act on the serotonin system can speed up recovery from jet lag, including 5-HTP, the metabolic precursor for serotonin, which is widely available as a “nutritional supplement.” Scientists have not yet run a gold standard clinical trial to test the supplement's effectiveness, however.

Research on circadian biology is moving at such a rapid pace that other possibilities will surely emerge in the near future. Travelers can start looking forward to reclaiming the first days of their trips.