Exercise can lead to more regular sleep patterns, an improved immune system, better brain function and a longer life, research suggests.
Glasgow University scientists found that old mice took longer to adapt to changes to their daily routine, but that their synchronisation improved if they had access to a running wheel.
Scientists adjusted the light and dark exposure of lab mice to advance their body clocks by eight hours and then returned them to a natural cycle.
The body clock is controlled by region deep in the brain called the suprachiasmatic nucleus (SCN), which is connected to the optic nerve in the eyes.
As organisms age, the body clock often become less synchronised which can result in poor sleep patterns, weakened immune function and general cognitive decline.
By studying the activity in the SCN scientists found young mice adapted quickly to changes, and old active mice adapted quicker than old inactive mice.
Professor Stephany Biello, of the Institute of Neuroscience & Psychology, said: "Ageing can impact the daily circadian rhythms leading to impaired sleep and activity cycles.
"Older adults show reduced amplitude of rhythms, manifested most obviously as disrupted sleep. In addition, ageing of the internal clock affects mood and memory.
"Rodents also show significant changes in circadian function with age making them a good model to study the mechanism of age-related changes.
"Synchronisation is key to a healthy immune function, metabolism and mood. Evidence suggests that animals that are more strongly synchronised live healthier and longer lives.
"Our study demonstrates that voluntary exercise has an impact on circadian rhythms and this has implications for the health of older people living with environmentally induced circadian disruption. It is also indicates another health benefit to regular exercise."