Inside each of us ticks a finely tuned master clock driven by a tiny region in the brain that keeps us in sync with Earth's cycle of light and dark. This master clock also directs a host of peripheral clocks found in organs, tissue and cells, says Michael Smolensky, adjunct professor of biomedical engineering at the University of Texas, Austin. "The body doesn't respond to medications in the same way at different times of the day," he says. "Some drugs are not as effective or as well tolerated if they're taken at the wrong biological time. It's not that they're not effective at all, but they're certainly much less effective."
In fact, drugs labeled "take one a day" often work better when taken at night. Modifying the timing of drugs to achieve the greatest benefit with the lowest risk of unpleasant side effects is called drug chronotherapy.
There have been tremendous advances in timing treatments for hypertension and rheumatoid arthritis, for example, according to Smolensky. And even some cancer treatments can be improved through chronotherapy. A drug called 5-fluorouracil (5-FU), used to treat colorectal cancer, is now given at night when these cancer cells are more vulnerable and normal cells are resting and least sensitive.
Although chronotherapy is a hot topic these days, your doctor or pharmacist may not be aware of it.
"Unfortunately, there's a disconnect between what's taught to doctors and what we know from chronotherapy research," says circadian biologist Georgios Paschos of the University of Pennsylvania School of Medicine. "Except for a few conditions, clinical medicine hasn't yet caught up with our findings," he says. But, he predicts, this will change in the next decade or two.
Here is what researchers have discovered about the best time to take your medicine. (Note: Never change the timing of your drugs without first discussing it with your doctor or pharmacist.)
When to take medicine: Take statins at bedtime, advises the British Heart Foundation.
Here's why: Cholesterol production in the liver is highest after midnight and lowest during the morning and early afternoon, so statins are most effective when taken just before bedtime.
High blood pressure
Blood pressure shows a 24-hour rhythm, higher during the day and lower during nighttime sleep. However, especially after age 55, many people with high blood pressure don't exhibit this nighttime dip, a condition called non-dipping.
When to take medicine: Take at least one blood pressure-lowering medication at bedtime. Drugs called ACE inhibitors and ARBs are the most effective when taken at this time.
Here's why: Non-dipping is a major risk factor for stroke, heart attack and kidney disease. Taking one or more of the prescribed medications just before bedtime normalizes daily blood pressure rhythm and significantly decreases the risk, studies have found.