henry copeland:

The link between circadian rhythms and aging: Gene associated with longevity also regulates the body's circadian clock -- ScienceDaily

Last year, Guarente found that a robust circadian period correlated with longer lifespan in mice. That got him wondering what role SIRT1, which has been shown to prolong lifespan in many animals, might play in that phenomenon. SIRT1, which Guarente first linked with aging more than 15 years ago, is a master regulator of cell responses to stress, coordinating a variety of hormone networks, proteins and genes to help keep cells alive and healthy.
- www.sciencedaily.com