[Aging and homeostasis. Circadian rhythms and aging.]

Daily rhythms of physiological and behavioral processes such as sleep and arousal are controlled by the circadian clock. The expression of the clock genes oscillate rhythmically in daily manner, and this clock oscillator resides in almost all of the cells in the body. The circadian clock entrains to diurnal environmental changes by using light and food intake as external time cues. Timing of feeding and fasting strongly affects daily rhythms in the expression of circadian clock genes and key regulators of nutrient homeostasis. Understanding roles of the clock oscillator system and feeding-fasting cycles lets us recognize the importance of timing of feeding, ultimately to adjust the aging-related changes in circadian rhythms.