Changes in brain architecture due to altered sleep/wake cycles

Our physiology is linked to the planet through circadian rhythms. Specifically, our sleep/wake cycle is synched to the 24-hour light/dark cycle of the Earth. What happens to the brain when the light/dark cycle is shortened from 24-hours to 20-hours?

Researchers at Rockefeller University studied this in mice. Mice exposed to a 20-hour light/dark cycle gained weight and some became obese. More bothersome and surprising was the development of alterations in brain architecture: dendrites (the projections that transmit information from other nerve cells to the body of the neuron) became shorter and the organization of nerve cells “in the prelimbic prefrontal cortex, a brain region important in executive function and emotional control” became less complex. The author's conclusion:

How our findings translate to humans living and working in chronic circadian disruption is unknown, but we believe that this model can provide a foundation to understand how environmental disruption of circadian rhythms impacts the brain, behavior, and physiology.

What is not known is whether these changes correct themselves after the mice are returned to the endogenous 24-hour cycle. Possibly this will be the subject of a subsequent study.

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