Circadian (daily) rhythms are evolutionarily ancient, present in almost all organisms, and regulate nearly every biological process. In our modern industrialized society, we have altered the relationship between our circadian rhythms and the day-night cycle. In many cases we are active long into the night and sleep during the day. In extreme cases, such as shift-workers and trans-meridian air travelers (e.g., jet-lag), overriding circadian rhythms can be more than just a nuisance. Chronically, this can lead to heath problems, including development of the metabolic syndrome, increased risk of heart disease, higher incidences of certain types of cancer, disrupted immune responses, and increased risk of suffering from a major depressive syndrome. Importantly, findings in both humans and non-human animals have demonstrated that there are relationships between changes in sleep and changes in addiction/relapse. However, these relationships have not yet been fully explored and represent a potentially major area for intervention. This is particularly important, given that in many psychiatric disorders, problems sleeping are one of the most reported, and distressing, symptoms. Moreover, disruption of sleep and circadian rhythms could result in additional psychological and physical pressures, potentially contributing to a positive feedback loop and exacerbating other aspects of disease.
Dr. Karatsoreos’ current research focuses on the relationship between circadian rhythms and mental and physical health, highlighting how circadian rhythms modulate physiology and behavior, as well as how disrupting them in animal models can produce physiological and behavioral abnormalities that change an animal’s susceptibility to further environmental or psychological stress. It is hoped that these models will provide an understanding of how dysregulation of the body’s timing and metabolic systems interact to produce changes in behavior and physiology, and will potentially lead to new clinical interventions to alleviate some of the physical and mental health consequences of our modern lifestyles.