Circadian Organization

Age-related changes in the circadian clock system may underlie various mental and physical disorders. Such changes could occur at many levels of circadian organization, including the input and output pathways to and from the central circadian clock located in the hypothalamic suprachiasmatic nucleus (SCN), as well as within the SCN itself. The recent discovery that most cells/tissues of the body contain the core molecular circadian clock, and regulate the diurnal expression of hundreds of clock-controlled genes, raises fundamental questions about aging of circadian timing systems at tissue and organ levels, both in the central nervous system and in the periphery. While aging can clearly disrupt circadian timing, chronic disruption of circadian timing may lead to an earlier occurrence of aging and age-related diseases.