Dr. Joseph Bass is the Charles F. Kettering Professor of Medicine, and the Chief of the Division of Endocrinology, Metabolism and Molecular Medicine at Northwestern University. Joseph Bass established links between molecular clocks and metabolism that have been at the forefront of studies of circadian biomedicine. He made the original discovery that disruption of the core molecular circadian clock leads to desynchrony between feeding and sleep cycles and promotes obesity, demonstrating that clock genes are essential for glucose and body weight homeostasis. He subsequently demonstrated that cellular clocks control hunger, insulin secretion, and mitochondrial function, and that an obesogenic diet dissociates clock cycles from the environment, revealing that circadian timing governs metabolic health. He also showed that the circadian clock regulates nucleotide metabolism, in turn modulating day/night cycles of mitochondrial respiration and exercise capacity. Active as both an endocrinologist and investigator, Bass has opened up a new field that is illuminating how molecular clocks control physiology at different times of day, with a broad range of medical implications including new avenues for treating diabetes and obesity.