The body’s most important biological clocks are actually in sync

Both the circadian clock, which regulates our sleep/wake rhythm, and the cell cycle, which regulates the growth, life, and death of cells in our body, are in sync. The synchronized interaction between the two most important “clocks” in the body might play a physiological role, a new study found.

The clocks of life

Researchers at EPFL’s Institute of Bioengineering in Switzerland developed a new mathematical model that analyzes the coupling of the two clocks by looking at time-lapse movies of thousands of single cells from mice and humans.

Using this model, the Swiss researchers were able to measure and predict phase shifts when the two clocks were synced in a 1:1 and 1:2 pattern.

Finally, the research team also modeled the clocks in a randomized way (stochastically) in order to better capture what happens in real cells.

The fact that the circadian-cell cycle synchronization was found to be common across different species, including humans, suggests there’s a fundamental biological mechanism behind it.

Although this wasn’t the object of the study, the findings may mean that the two clocks depend on each other. So, for a shift worker whose circadian clock is all messed up, this might have effects on the lifecycle of their cells. Likewise, the inner workings of a person’s cells might cause shifts in the circadian rhythm, resulting in poor sleep patterns. Perhaps a new study might investigate this relationship closer.

“This interaction might play a physiological role,” says Felix Naef, a researcher at EPFL and lead author of the new study. “It can explain why different body tissues have their clocks set at slightly different times, a bit like world time zone wall clocks in an airport.”

The findings appeared in the journal Nature Physics.