Scientists hope the research could help tackle sleep disorders
Our internal body clocks are shaped by the weather as well as by the seasons, scientists have discovered.
Researchers used computers to model the workings of internal biological clocks.
They found the mechanism had to be so complicated because it was able to deal with varying amounts of light from hour to hour, as well as changing seasons.
It is hoped the research, led by a team from Edinburgh University, could help tackle sleep problems caused by jet lag and shift working.
The researchers said the findings gave them a greater understanding of what drives the internal rhythms of people, animals and plants.
Environmental signals, such as hours of daylight, affect the daily rhythms which many plants use to control flowering and ripening.
The findings may also help scientists develop crops that can cope with climate change.
The study was led by the University of Edinburgh, and involved researchers from the California Institute of Technology and the University of Warwick.
Dr Carl Troein, of the University of Edinburgh's School of Biological Sciences, said: "By better understanding why biological clocks are so complex, we stand a better chance of controlling them.
"Our study goes some way to explaining how and why these in-built rhythms have developed. We hope it will be useful in informing treatments for sleep disorders as well as helping scientists develop crops that can survive in the long term."
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