Tokyo, Mar 21 (IANS): Scientists have identified three new genes that allow cells to adapt to daily changes in environmental conditions by adjusting their internal "body clock" or the circadian clock responsible for regular sleep-wake cycles.

Circadian rhythms are found in almost all organisms with sensitivity to light.

The new discovery by the University of Tokyo scientists revealed for the first time that circadian regulation may be directly connected to cellular stress.

The study revealed that signal-regulating kinase 1, 2, and 3 (Ask1, Ask2, Ask3) genes are necessary in order to respond to both sudden changes to the environment and gradual changes over time.

Normal mice were found to be able to change their wake-up time the next morning after unexpected light exposure during the night, as measured by their activity running on a wheel.

However, mice without the Ask genes have less ability to synchronise their circadian clock to changes in environmental light-dark cycles, the researchers said, in a paper published in the journal Proceedings of the National Academy of Sciences.

"Many researchers in this field have long suspected oxidative stress and circadian rhythms are somehow connected because of the cycles of photosynthesis and DNA replication we see even in ancient organisms," said Yoshitaka Fukada, Professor at the University of Tokyo.

"We are very excited about our results because we can approach the origin of the circadian clock by connecting oxidative stress and circadian regulation through the Ask genes," Fukada added.

The disruptions in circadian rhythms, especially among shift workers and elderly, are related to increased risk of high blood pressure (hypertension), metabolic disorders and insomnia.

The research can show hints for later drug discovery for a tool to regulate circadian rhythms, Fukada said.