Researchers from the University of Pennsylvania have established that the body goes through changes in a 24-hour cycle, affecting how effective taken medication can be. Prescriptions note when a dose should be taken, right? The study builds upon that practice of timing medication by specifically exploring the role of internal body clocks in the process.

Published in the Proceedings of the National Academy of Sciences, the five-year project outlined that the best-selling drugs of today (56 out of 100 to be exact) target proteins in the body change activities during the day. Given this, taking medication at the precise moment the protein it is targeting is receptive may mean better results.

This isn't the first time that body clocks were studied to improve the effectiveness of medication but only a few organs have been analyzed in the past. This time, more organs were observed, providing a better picture of how internal rhythms affect medications.

Researchers carried out the study by investigating the impact time of day has on how DNA functions in mice. Mice are best candidates for the study because they use more or less the same molecular mechanisms as humans in keeping time.

Every two hours, samples from the skeletal muscle, lung, hypothalamus, heart, white fat, brown fat, cerebellum, brain stem, aorta, adrenal gland, lung, liver, and kidney were observed. Results showed that 43 percent of the genes involved in manufacturing proteins change activities throughout the day.

Different genes in different tissues featured different activity patterns and this has led researchers to conservatively estimate than over 50 percent of genes would show fluctuations daily if every tissue in the body were to be sampled.

Out of all the samples, liver tissues were the most dynamic, with 3,186 of its genes expressing daily patterns compared to the hypothalamus which had just 642.

A lot of medications don't last long in the body so it is necessary for a dosage to be administered at the right time, taking advantage of when it would be most effective. Aside from simply improving effectiveness though, taking medications at the right time of the day could also help alleviate potential side effects.

According to lead researcher John Hogenesch, the next step for the study is to apply its results to specific animal models. Eventually, it will call for rigorous clinical trials to truly determine optimal timing for medications.

Other members of the research team include: Michael Hughes, Heather Ballance, Nicholas Lahens, and Ray Zhang.