Israeli scientists have developed an innovative method to track the human body’s circadian rhythms, finding in a new peer-reviewed study that female sex hormones have a dramatic effect on the setting of these internal circadian clocks.

Every human body has a central circadian clock in the brain that helps control its daily rhythms — but there are also circadian clocks within almost every cell in the body that follow their own tick-tocking beat.

The researchers mapped circadian clocks across many cells using their method, called CircaSCOPE, to find that female sex hormones — especially progesterone — along with the stress hormone cortisol, have a dramatic effect on the setting of these internal timers.

When these clocks are not coordinated, people can experience serious health problems, including sleep disorders, diabetes and cancer.

The body “needs to synchronize millions of clocks because they are present in every cell in our body,” said Prof. Gad Asher of the Weizmann Institute of Science’s Asher lab, recently speaking to The Times of Israel.

“Sex hormones are very important in shifting the clock,” Asher said. “Female hormones have a much more prominent effect compared to male hormones.”

Men also have progesterone, but in much smaller amounts than women. The hormone can act as a building block for other hormones in the body and also affects the brain and nervous system.

Asher noted that the experiments were done in cell cultures and have not yet been tested in animals or humans.

However, he said, “we now know how these clocks communicate, so maybe we can explain their involvement in various disorders and pathologies, and help patients whose internal timing is disrupted.”

The study, led by Dr. Gal Manella, Dr. Saar Ezagouri, and Nityanand Bolshette, was published in the scientific journal Nature Communications.

In the past, Asher said, “people thought that there is only one main clock in the brain which responds to light and dark and coordinates our daily physiology, metabolism, and behavior.”

Then, about 25 years ago, scientists discovered that........

© The Times of Israel