It is already known by scientists that some genes are controlled by the circadian clock and only turn on once during each 24-hour cycle. It is also known that these genes coordinate physiological and behavioural processes on a 24 hour rhythm. Researchers at the University Of Pennsylvannia School Of Medicine and the Salk Institute for Biological Studies have given the first report which uncovers that some genes are also switched on every 12 or 8 hours.
To uncover these shorter oscillations the team isolated the livers of mice every hour for 48 hours to look at gene activity. Through microarray analysis, they found that more than 3,000 genes were expressed on a circadian rhythm and additionally 260 genes were expressed on a 12 hour cycle and 63 on an 8 hour cycle.
A scientist in the article stated that there was an obvious biological bases to a 12-hour rhythm and that the 12-hour genes were predicted to turn on and off at dawn and dusk. It was stated by Hogenesch that, “These (dawn and dusk) are two really, really stressful transitions that your body goes through. Anybody who has young children realises that they are more likely to cry around those times..”.
Hogenesh also stated that although scientists have less of a handle on the 8-hour rhythms there is the possibility that there could be biological bases to an 8-hour work day.
These studies indicate that shorter cycles of the circadian rhythm are also biologically encoded and this discovery will help scientists understand disruptions to the normal circadian cycle. The study is further detailed in a report by scientists of the Salk Institute for Biological Sciences.
Reference:
University of Pennsylvania School of Medicine (2009) A Biological Basis for the 8 Hour Workday? United States of America: University of Pennsylvania School of Medicine
Available From: http://www.medicalnewstoday.com/articles/147375.php
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