Association between mammalian lifespan and circadian free-running period: the circadian resonance hypothesis revisited

Abstract

Biological rhythms that oscillate with periods close to 24 h (circadian cycles) are pervasive features of mammalian physiology, facilitating entrainment to the 24 h cycle generated by the rotation of the Earth. In the absence of environmental time cues, circadian rhythms default to their endogenous period called tau , or the free-running period. This sustained circadian rhythmicity in constant conditions has been reported across the animal kingdom, a ubiquity that could imply that innate rhythmicity confers an adaptive advantage. In this study, we found that the deviation of tau from 24 h was inversely related to the lifespan in laboratory mouse strains, and in other rodent and primate species. These findings support the hypothesis that misalignment of endogenous rhythms and 24 h environmental cycles may be associated with a physiological cost that has an effect on longevity.

Accelerated protein evolution analysis reveals genes and pathways associated with the evolution of mammalian longevity

“…A more intuitive explanation of the evolution of longevity is due to selection of proteins in common pathways and biological processes, and thus, our analysis of GO categories provides novel clues about the processes involved in species differences in aging. Interestingly, we found functional categories showing specificity of selection in MLI branches which have been previously associated to aging such as actin cytoskeleton (Gourlay and Ayscough 2005), 1-phosphatidylinositol-3-kinase activity, phosphoinositide 3-kinase complex, response to food, and circadian rhythm (Wyse et al 2010). Moreover, many of our highly ranked functional categories may have been selected for due to their contribution to the evolution of longevity.…”

The aging clock: circadian rhythms and later life

“…Given the centrality of the circadian clock to so many vital human physiological functions, deeper insights into how age-related changes in the clock arise may be far more influential for human health and longevity than anticipated. In support of this, analyses of the variability of the free-run circadian period (τ) in several species suggest a negative relationship between lifespan and deviation of τ from 24 hours (153,154).…”

Circadian Rhythms, Aging, and Life Span in Mammals

“…Some rodents, such as hamsters, rats, and deer-mice, show a shortening of their endogenous period, tau, with age (141,176), whereas some mouse strains show lengthening of the period (72, 119,120,142). A positive link between tau close to 24 h and survival has been previously suggested (82,190). According to this hypothesis, tau longer or shorter than 24 h necessitates a daily synchronization to external time cues (i.e., light/dark cycles) with a physiological cost proportional to the deviation that might affect survival.…”