WVU School of Medicine faculty research suggests effects of light at night carry generationally

Disrupting the natural circadian rhythms by exposure to light at night of a parent could lead to immune deficiency in the offspring, even if the offspring is raised without ever being exposed to light at night themselves.

Randy Nelson, Ph.D., department chair and professor in the WVU School of Medicine Department of Neuroscience, worked with Yasmine Cissé, Ph.D., from the University of Maryland on the study as part of her thesis. Nelson has a long history of research regarding circadian rhythms and the response when the natural cycle of daylight and nighttime is altered.

“We know some metabolic, immune and behavioral responses are optimized to occur at certain times of the day, and exposure to light at night resets that internal clock,” Nelson explained. “We’ve established that in adult rodents, interrupting circadian rhythms by light at night leads to a weakened immune response.”

When we present those findings, and explained we used a light output similar to a child’s night light to interrupt the circadian rhythm, that begs the question, what effect does that light have on human children.” 

While research that directly correlates the study to humans is still pending, what Nelson and his colleagues found in rodent populations surprised them. A constant, low-light disruption in a rodent’s circadian rhythm carried over to their offspring in the form of a lowered immune response.

The study looked at innate immune responses, noting that males whose parents were exposed to light before conception had exaggerated fever responses and females had more circulating bacteria-killing factors.

“It’s noteworthy that the effects carried over even though the offspring had always been exposed to a natural cycle of light and dark,” Nelson said. 

Cissé noted the study contributes to growing evidence that fathers are important in determining offspring outcomes.

“Fathers are important for programming their offspring, and many studies suggest that paternal exposure to stress/trauma, infection, alcohol, and poor diet prior to conception can be passed on to future generations,” she explained.

Nelson and his colleagues will continue to expand on the study, which was recently published online with the Public Library of Science.  The team will look at the outcomes generationally, seeing if the effects translate to the “grand” generation, and if there were other epigenetic factors playing a role.

 “While there are differences in species, we all share a common circadian clock location in the hypothalamus, common clock genes and molecular clock works. Additional work on disrupted circadian rhythms is warranted in humans,” he added.

Cissé added good circadian hygiene is important for everyone, regardless of age and gender, and this study adds proper circadian function to the growing field of paternal preconception experiences that affect future generations.

This research was supported by the National Science Foundation Division of Integrative Organismal Systems award number 11-18792 to Randy J. Nelson and National Institute of Environmental Health Sciences award number ES026890-02 to Yasmine M. Cissé.

To learn more about the Department of Neuroscience, visit https://medicine.hsc.wvu.edu/neuroscience/.