Art by Jenna Fite. Photograph by Rebecca Hale, NGM Staff
Art by Jenna Fite. Photograph by Rebecca Hale, NGM Staff

When You Take Your Medicine Matters

A pill popped at the wrong time of day might not work.

This story appears in the June 2016 issue of National Geographic magazine.

They say there’s a time for everything—though you might not know it from looking at a pill-bottle label. Most say how many pills to take but not when to take them. That’s a problem, “because symptoms and treatment efficacy vary by time of day,” says University of Texas at Austin biomedical engineering professor Michael Smolensky. Strokes, for instance, tend to occur in the morning; asthma usually flares up at night. “If you take your medication at the wrong time,” he says, “it may not work as well … or you could experience more side effects and toxicity.”

Humans and animals have a set of internal clocks in their brains, organs, tissues, and cells that naturally sync with Earth’s 24-hour light-dark cycle. Timing medications to those circadian rhythms is called chronotherapy—a field still foreign to many prescribers. Circadian biologist Georgios Paschos of the University of Pennsylvania School of Medicine suggests a remedy: “more clinical trials that investigate the optimal timing of drug administration.”