About Circadian Rhythms

Daily, or circadian, rhythms are a fundamental component of biological organisms, including humans. These rhythms are generated within the body. Circadian rhythms help coordinate the timing of our internal bodily functions, including sleep, as well as our interactions with the external world. While the class of biological rhythms that represents the main focus of the Center for Sleep & Circadian Biology is that with a period of about 24 hours (i.e., circadian), attention is also given to biological timing processes that repeat themselves every few hours (i.e., ultradian rhythms) or on a yearly basis (i.e., seasonal rhythms).

The relatively new field of biological rhythms research has reached a state of maturity where tremendous advances, at both the basic science and clinical levels, can be expected to be made over the coming decade. Only recently has the medical community, as well as the general public, become aware of the importance of circadian rhythms for human health, safety, performance and productivity. It is now recognized that physical and mental abnormalities are associated with night-work, which involves over 20% of the work force in industrialized countries, and rapid travel across time zones (i.e., "jet lag").

The pharmaceutical industry is now investigating the importance of circadian rhythms for the timing of drug delivery and is interested in developing drugs that could affect the circadian clock of humans, as well as agricultural plants and animals. Numerous health problems, including some forms of depression, as well as many sleep, neurological, cardiovascular and endocrine disorders, have recently been associated with circadian rhythm dysfunctions.

In addition, as the elderly continue to become a greater percentage of the population in the United States, as well as in the rest of the world, more and more circadian abnormalities are being observed in older people suffering


from various sleep, mental and physical disorders (including dementia). Advances in our understanding of circadian rhythms will have broad economic implications, since information from fundamental research programs on circadian rhythms can be expected to be transferred readily to the medical, business and agricultural sectors. There is a growing need for many industries that employ workers around the clock (e.g., transportation, utilities, public safety, heavy manufacturing and many service industries) to receive advice and information from scientifically reputable sources regarding work schedules. The use of circadian principles to manipulate the breeding seasons of many plant and animal species, which could enhance agricultural productivity, is now possible.

The growing awareness of the various and numerous ways in which a better understanding of circadian rhythms could impact human health is why the recent NIMH report to the U.S. Congress on the "Decade of the Brain" has targeted the study of circadian rhythms as one of the main areas in which basic neuroscience research could be transferred to the clincial community for the benefit of mankind. Indeed, in recent years, numerous of the National Institutes of Health have held workshops on circadian rhythms and health. Northwestern University is in a position to play a leading role in this emerging area of biomedicine, and the decision to establish the Center for Sleep & Circadian Biology at Northwestern was taken in order to enhance the activities of the investigators performing research on sleep and biological rhythms within the University.

To access recent scientific publications by CSCB researchers, click here.

Every scientific field has its specific terminology; the scientific area of biological rhythms and sleep is no exception. To access a glossary that defines some of the terms that readers may encounter when reading about the field, click here.

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