Doctors may tell patients to pop their pills in the morning or evening or perhaps with meals. But a new study finds many genesthat direct production of proteins targeted by drugs have a daily cycle of activity driven by the body’s circadian rhythms. Medication to manage a hyperactive thyroid, for example, could therefore be most effective if consumed when certain thyroid genes are most active. Conversely, taking the drug when the genes are idle could be ineffective. Also, says Marc D. Ruben, a research fellow at Cincinnati Children’s Hospital, who led the study, smart timing “could reduce the amount of drug needed to achieve a desired effect or lessen side effects at the same dose.”