Circadian clocks coordinate the organism to the alternating cycles of day and night. Scientists have studied how these clocks work in polar regions where days or nights can last for weeks.

In temperate latitudes, the right timing is crucial for almost all living things: Plants sprout with the advent of spring, bees know the best times to visit flowers, people get tired in the evening and wake up again in the morning. The constant change between light and dark, day and night is the rhythm to which all living beings must adapt if they want to survive and reproduce. Circadian clocks help them achieve this by regulating the timekeeping mechanism in each organism and adjusting it to changes.

But what happens in environments where the day-and-night cycle no longer follows the typical 24-hour rhythm as in the polar regions, when twilight is directly followed by dawn or when the sun is low above the horizon only for a few hours each day? Scientists from the Department of Neurobiology and Genetics of the University of Würzburg have looked into these questions; Dr. Pamela Menegazzi was in charge of the study. The team has published its results in the latest issue of Current Biology.

“Circadian clocks with a periodicity of about 24 hours enable animals to adapt to the day-and-night cycles. However, if these clocks are too rigid, this could be a disadvantage when adapting to weakly rhythmic environments like the polar regions,” Menegazzi describes the background of the new study. She explains that several high-latitude species that live in the far north or south are known to no longer adapt their activities to a 24-hour rhythm but have adopted an arrhythmic behavior instead.

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