Synchronizing drug delivery with a patient’s body clock can yield clear benefits. Nature asks: Will the data be enough to overcome long-standing hurdles?

More than four decades of studies describe how accounting for the body’s cycle of daily rhythms — its circadian clock — can influence responses to medications and procedures for everything from asthma to epileptic seizures. Research suggests that the majority of today’s best-selling drugs, including heartburn medications and treatments for erectile dysfunction, work better when taken at specific times of day.