A group of Cambridge scientists have successfully identified the mechanism that drives our internal 24-hour clock, or circadian rhythm. It occurs not only in human cells, but has also been found in other life forms such as algae, and has been dated back millions of years. Whilst the research promises a better understanding of the problems associated with shift-work and jet-lag, this mechanism has also been proven to be responsible for sleep patterns, seasonal shifts and even the migration of butterflies.

The study from the Institute of Metabolic Science at the University of Cambridge discovered that red blood cells contain this 24-hour rhythm. In the past, scientists assumed this rhythm came from DNA and gene activity but unlike most cells, red blood cells do not contain DNA.

During this study, the Cambridge scientists incubated healthy red blood cells in the dark at body temperature for several days, sampling them at regular intervals. It was discovered that the levels of peroxiredoxins (proteins that are produced in blood), underwent a 24-hour cycle. Virtually all known organisms contain peroxiredoxins.

"The implications of this for health are manifold," said Akhilesh Reddy, lead author of the study. "We already know that disrupted clocks – for example, caused by shift-work and jet-lag – are associated with metabolic disorders such as diabetes, mental health problems and even cancer. By furthering our knowledge of how the 24-hour clock in cells works, we hope that the links to these disorders – and others – will be made clearer. This will, in the longer term, lead to new therapies that we couldn't even have thought about a couple of years ago."

A second study by scientists working together at the Universities of Edinburgh and Cambridge, and the Observatoire Oceanologique in Banyuls, France, identified a similar 24-hour rhythm in marine algae. Once again, the scientists held a previous belief that the circadian clock was driven by gene activity, but both the algae and the red blood cells proved this theory wrong.

"This groundbreaking research shows that body clocks are ancient mechanisms that have stayed with us through a billion years of evolution," said Andrew Millar of the University of Edinburgh's School of Biological Sciences. "They must be far more important and sophisticated than we previously realized. More work is needed to determine how and why these clocks developed in people – and most likely all other living things on Earth – and what role they play in controlling our bodies."

The papers "Circadian Clocks in Human Red Blood Cells" and "Circadian Rhythms Persist Without Transcription in a Eukaryote" were published on 27th January 2011 in the journal Nature.