How artificial light at night damages brain health and metabolism

MORGANTOWN, West Virginia, USA, 8 July 2025 – In a comprehensive Genomic Press Innovators & Ideas interview published today, distinguished neuroscientist Dr. Randy J. Nelson shares insights from his pioneering research on how disrupted circadian rhythms affect brain function and overall health. The interview, published in Brain Medicine, traces Dr. Nelson's unconventional path from farm work and autopsy assistant to becoming one of the world's leading authorities on biological rhythms.

Dr. Nelson, who chairs the Department of Neuroscience at West Virginia University, has spent the past decade uncovering the hidden dangers of artificial light exposure. His research demonstrates that light at night doesn't just affect sleep quality; it fundamentally alters immune function, triggers neuroinflammation, disrupts metabolism, and influences mood regulation.

From Turkey Processing Plant to Top Research Institution

The interview reveals Dr. Nelson's remarkable journey to academic prominence. After working night shifts at a turkey processing plant during high school and later conducting postmortem examinations at two Cleveland hospitals, he eventually found his way to the University of California, San Diego, through an unexpected job opportunity at the San Diego Zoo.

"My path to academia is typical in the sense that it is not 'typical,'" Dr. Nelson reflects in the interview. His unique background, including becoming the first person in the United States to simultaneously earn two separate PhDs (in Psychology and Endocrinology from UC Berkeley), shaped his integrative approach to neuroscience research.

Circadian Disruption: A Modern Health Crisis

Dr. Nelson's laboratory has published groundbreaking findings on how exposure to artificial light at night affects multiple body systems. The research goes beyond simple sleep disturbance to reveal profound effects on physiological processes that evolved over millions of years to function in sync with natural light-dark cycles.

Key areas of impact identified by Dr. Nelson's research include immune system dysfunction, where light exposure at inappropriate times can suppress typical immune responses or trigger excessive inflammation. The work also demonstrates clear links between circadian disruption and metabolic disorders, potentially contributing to the obesity epidemic. Perhaps most concerningly, the research shows direct effects on mood regulation, with implications for understanding depression and anxiety disorders.

What specific wavelengths of light are most disruptive to circadian rhythms? How quickly can the body recover from chronic light exposure? What is the contribution of time-of-day as a biological variable? These questions drive ongoing investigations in Dr. Nelson's laboratory.

Translating Discovery to Clinical Practice

Moving beyond foundational research, Dr. Nelson's team currently conducts clinical trials examining whether blocking disruptive light effects can improve outcomes for intensive care patients. Two major trials focus on stroke recovery and cardiac surgery patients, populations particularly vulnerable to the harsh lighting conditions typical of hospital ICUs.

"Circadian rhythms are a fundamental aspect of biology, and much is known from foundational science about them," Dr. Nelson explains. "However, little of this foundational science has been translated to clinical medicine."

The research also extends to healthcare workers themselves. A third clinical trial investigates whether bright blue light visors can help night shift nurses reset their circadian rhythms, potentially improving their sleep quality, cognitive performance, and mood. Could similar interventions help other shift workers across various industries maintain better health despite irregular schedules?

Time as a Biological Variable

One of Dr. Nelson's most provocative proposals involves recognizing time-of-day as a crucial biological variable in all research. He argues that experimental results can vary dramatically depending on when studies are conducted, yet this information rarely appears in scientific publications.

"The answer to an experimental question may depend in part on the time-of-day when the question is asked," Dr. Nelson notes. This observation has profound implications for research reproducibility and could explain why some studies fail to replicate previous findings.

Building the Next Generation of Neuroscientists

Throughout his career at Johns Hopkins University, Ohio State University, and now West Virginia University, Dr. Nelson has mentored 25 PhD students and 16 postdoctoral researchers. His leadership philosophy emphasizes creating supportive environments where young scientists can thrive. His mentoring philosophy has been featured in a recent Society for Neuroscience Neuronline podcast (https://podcasts.apple.com/us/podcast/joy-and-curiosity/id1765339956?i=1000696714548).

As current president of the Association of Medical School Neuroscience Department Chairs, Dr. Nelson advocates for resources and policies that support early-career researchers. He particularly values helping faculty members navigate the challenging early stages of their careers through strategic resource allocation and mentorship.

What role might circadian rhythm research play in addressing the mental health crisis among graduate students and postdocs? How can academic institutions better support work-life integration for researchers studying around-the-clock biological processes?

A Vision for Healthier Living

Dr. Nelson's research carries immediate practical implications for public health. Simple interventions like reducing evening screen time, using warmer light colors after sunset, and maintaining consistent sleep schedules could significantly impact population health. His work suggests that respecting our evolutionary heritage by aligning modern life more closely with natural light patterns could prevent numerous chronic health conditions.  He recently published a trade book with Oxford University Press entitled, “Dark Matters,” to help the general public appreciate the importance of good circadian hygiene for health and wellness.

The interview also touches on Dr. Nelson's personal interests, including travel, biking, and gardening, activities that keep him connected to natural rhythms. His favorite place remains Southern California, where his academic journey began through that serendipitous opportunity at the San Diego Zoo decades ago. Dr. Randy J. Nelson's Genomic Press interview is part of a larger series called Innovators & Ideas that highlights the people behind today's most influential scientific breakthroughs. Each interview in the series offers a blend of cutting-edge research and personal reflections, providing readers with a comprehensive view of the scientists shaping the future. By combining a focus on professional achievements with personal insights, this interview style invites a richer narrative that both engages and educates readers. This format provides an ideal starting point for profiles that explore the scientist's impact on the field, while also touching on broader human themes. More information on the research leaders and rising stars featured in our Innovators & Ideas – Genomic Press Interview series can be found in our publications website: https://genomicpress.kglmeridian.com/.

The Genomic Press Interview in Brain Medicine titled "Randy J. Nelson: Disruption of circadian rhythms on brain function and health," is freely available via Open Access on 8 July 2025 in Brain Medicine at the following hyperlink: https://doi.org/10.61373/bm025k.0083.

About Brain Medicine: Brain Medicine (ISSN: 2997-2639, online and 2997-2647, print) is a high-quality medical research journal published by Genomic Press, New York. Brain Medicine is a new home for the cross-disciplinary pathway from innovation in fundamental neuroscience to translational initiatives in brain medicine. The journal's scope includes the underlying science, causes, outcomes, treatments, and societal impact of brain disorders, across all clinical disciplines and their interface.

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