Date Time ‘Junk DNA’ plays a key role in regulating our circadian clocks If you’ve ever had a bad case of jet lag, you know how a disruption to your body’s circadian rhythm makes it difficult to function. Molecular circadian “clocks” exist in cells throughout the body, governing more than just sleep and wake cycles — they are crucial to many aspects of human health. For more than a decade, researchers have been trying to figure out what makes them tick, in search of new insights into diseases like Alzheimer’s, cancer and diabetes. Until now, that research has focused on what is known as clock genes, which encode proteins that drive oscillating cycles of gene expression affecting physiology and behavior. But research just published in the Proceedings of the National Academy of Sciences reveals the discovery of a new cog in the circadian clock — a genome-wide regulatory layer made up of small chains of non-coding nucleotides known as micro RNAS (miRNAs).