Shimon Amir is an international leader in the study of behavioral neuroscience and regulatory physiology. He is known for early seminal work on the roles of endogenous opioids and in pain and stress, and his recent studies on brain mechanisms of circadian rhythms. His discoveries that the effectiveness of daylight as a clock-resetting stimulus varies with emotional state and is subject to Pavlovian conditioning have implications for the regulation of circadian rhythms in humans. His discovery of circadian oscillators in brain regions controlling emotion represents an important advance in the understanding of the relationship between emotional states and circadian rhythms.