The circadian patterns in mammals mostly follow 24-hours cycle. A lot of studies show that maintaining circadian cycle is very important to the health, disruption of it could lead to obesity and even diabetis. Scientists also reported about direct correlation of circadian cycle and lifespan. The more robust circadian cycle is, the longer life you live. This link direct scientists to find gene-manager of the circadian cycle .
SIRT1 is known as regulator of cell's responce to stress, hormone's level and a lot of other signaling pathways, that help cell to stay healthy. Leonard Guarente from MIT conducted an experiment on mice. He studied three gpoups of mice. The first one had lack in SIRT1 expression, the second one was a group with nornal SIRT1's level of expression, and the third one overexpressed the gene. Level of gene expression was observed in the brain. The experiment revialed that mice with larger amount of gene's copies do not suffer from age-dependent decline in circadian cycle.
Thus it becomes possible to prevent age-related deseases by using SIRT1 enhancers. Unfortunately, in order to be helpfull, the drug should be directed to the brain and nowadays there is no such medicine that could overcome blood-brain barrier.