Scientists have found our body's "rush hour" after identifying large shifts in activity just before dawn and dusk. This finding could help further develop our understanding of our body’s natural function and lead to more effective drug therapies without having to spend money on the developments of new drugs.

The idea of medications being more effective if taken at certain times of the day, called chronotherapy, is an observation doctors have understood for some time now. For example, as reported by the BBC, because heart disease is largely caused by cholesterol, which is mostly made by the liver during the night, doctors recommend taking statins in the evening for optimal effectiveness. Asthma and arthritis medication are also examples of time-sensitive medication. However, a new study conducted by scientists at the University of Pennsylvania could revolutionize this field.

The team used mice to study the effect of time on certain organs. They looked at samples from the kidney, liver, lung, adrenal gland, aorta, brainstem, cerebellum, brown fat, white fat, heart, hypothalamus, and skeletal muscle every two hours, the BBC reported. Results showed that 43 percent of the genes involved in protein manufacture altered their activity depending on the time of day, with the liver being, by far, the most dynamic of all the organs.

According to Dr. John Hogenesch, there are many opportunities for this finding, with 56 of the top 100 selling drugs being affected by genes identified to be time-sensitive in his study. "I'm hopeful that we can use this information to design better therapies with existing drugs, and that's huge because it's not going to cost any more money,” Hogenesch told the BBC.

Our biological clocks control the inner workings of our body, taking cues from changes in the weather and time of day. For example, when it gets darker, our body releases a hormone which makes us drowsy and ready for sleep, and many individuals experience significant changes in their moods that are connected to changes in the weather, including other bodily functions, such as our blood pressure, blood coagulation, and blood flow.

Dr. Simon Archer, a body clock scientist from the University of Surrey agreed with Hogenesch’s belief that this study could revolutionize the way doctors prescribe medication. “Thousands, millions of people potentially, could benefit from taking their medication at a different time of day, and raising this kind of awareness is important," Archer told the BBC. 

Source: Hogenesch JB, Zhang R, Lahens NF, et al. A circadian gene expression atlas in mammals: Implications for biology and medicine. PNAS. 2014.