Circadian physiology changes with aging: age is just a number, but circadian physiology keeps time

Circadian rhythms are inherent cycles of physiology and behavior that occur over approximately 24 h and are modulated by the cell-autonomous molecular clock. The molecular clocks throughout the body are aligned by the suprachiasmatic nucleus to contribute to robust daily variation of physiology, including core temperature, blood pressure, and heart rate. Alterations to the alignment of circadian clocks and changes to circadian rhythms of behavior and physiological processes are contributors to parameters that impact health and disease. In this review, we summarize what is known about changes to circadian rhythms of human behavior and physiology during older adulthood and the opportunities for future investigation of circadian physiology in older adults.