Researchers Work to Reset Circadian Rhythm

A new area of study may make it easier to adjust to the problems of jet lag or night-shift work.

Although the science is not quite there, recent work by Drs. Marc Cuesta, Nicolas Cermakian and Diane B. Boivin from the Douglas Mental Health University Institute and McGill University, both in Montreal, Canada, suggest resetting the body’s different biological clocks is a distinct possibility.

Physiological changes over the course of a day are regulated by a system comprised of a central clock located deep within the center of the brain and multiple clocks located in different parts of the body.

This study included 16 healthy volunteers who were studied in time-based isolation chambers. Researchers discovered that the peripheral biological clocks located in white blood cells can be synchronized through the administration of glucocorticoid tablets.

Study findings have been published in The FASEB Journal (published by the Federation of American Societies for Experimental Biology).

Since humans are fundamentally daytime creatures, staying awake at night can significantly disrupt all of the body’s internal biological clocks. Over the long term these disruptions can lead to a high incidence of various health problems, such as metabolic or cardiovascular problems or even certain types of cancer.

“Problems adjusting to atypical work schedules are a major issue for society. Our previous studies clearly show that desynchronized circadian clocks disrupt the sleep, performance, and cardiac parameters of night-shift workers,” Bovin said.

“However, current approaches to these problems have significant limitations, as a single therapy can’t address the disruptions that occur in all biological clocks. For example, when used incorrectly, light therapy can even aggravate the situation.”

Researchers admit that they still do not fully understand the mechanisms through which peripheral biological clocks adapt to night-shift work in humans. However, it is believed that these clocks essentially depend on the central clock.

“Clock genes are what drive our biological clocks, and these genes are active in all of our organs,” Cermakian said.

“Animal studies have shown that our central clock (in the brain) sends signals to the clocks in our other organs. Glucocorticoids appear to play a central role in transmitting these signals. However, until now, no one had demonstrated that cortisol (a glucocorticoid) plays this role in humans.”

Said Cuesta, “We studied the rhythmic expression of clock genes in white blood cells to see how they adjusted in response to glucocorticoids. These cells are involved in our body’s reaction to attacks from many pathogens.

“This study therefore suggests that biological rhythms may play a role in controlling immune function in night-shift workers.”

The previous work of Boivin and her team showed that exposing workers to bright light at night tor adjusting work schedules can improve the synchronization of the central biological clock to their atypical work schedule.

This new scientific discovery suggests innovative therapies could influence the different parts of the circadian system so that these rhythms can be adjusted to inverted sleep schedules.

These studies have possible applications for travelers, night-shift workers, patients suffering from sleep disorders, and circadian rhythm disorders, as well as people with various psychiatric disorders.

“At this stage, we are not recommending the use of glucocorticoids to adjust the rhythms of night-shift workers, as there could be medical risks,” explained Boivin.

“However, these results lead us to believe that we may one day be able to use a combined therapy that targets the central clock (inverting work schedules, administering controlled light therapy) with a pharmacological treatment that targets the peripheral clocks to ensure that all clocks are adjusted.”

Source: Douglas Mental Health University Institute/EurekAlert