A biological basis for the 8-hour workday?
The circadian clock coordinates physiological and behavioural processes on a 24-hour rhythm, allowing animals to anticipate changes in their environment and prepare accordingly. Scientists already know that some genes are controlled by the clock and are turned on only one time during each 24-hour cycle. Now, researchers at the University of Pennsylvania School of Medicine and the Salk Institute for Biological Studies found that some genes are switched on once every 12 or 8 hours, indicating that shorter cycles of the circadian rhythm are also biologically encoded. Using a novel time-sampling approach in which the investigators looked at gene activity in the mouse liver every hour for 48 hours, they also found 10-fold more genes controlled by the 24-hour clock than previously reported...