Can't sleep? Grabbing your phone and doomscrolling in the middle of night can doom your sleep-wake cycle. (© Point of view - stock.adobe.com)

In A Nutshell

Disrupted circadian rhythms from artificial light at night can affect immune function, neuroinflammation, metabolism, sleep, and mood.

Dr. Randy Nelson’s lab is testing real-world solutions like blocking disruptive light in ICUs and using bright blue light visors for night shift nurses.

He advocates for better awareness of time-of-day effects in research and everyday life.

Simple changes like limiting nighttime blue light could help protect your brain’s natural rhythms.

MORGANTOWN, W.V. — It’s 2 a.m., and instead of sleeping, someone is scrolling through their phone under bright hospital lights, working the night shift at a factory, or binge-watching Netflix until dawn. What seems like harmless modern behavior might actually be wreaking havoc on the brain in ways scientists are only beginning to understand.

Dr. Randy Nelson, who chairs the Department of Neuroscience at West Virginia University, has spent the last 15 years investigating something that affects millions of Americans daily: how exposure to artificial light at night disrupts our internal biological clocks and fundamentally alters brain function. His research examines how disrupted circadian rhythms affect “immune function, neuroinflammation, metabolism, sleep, and mood.”

Nelson studies shift workers and hospitalized patients, groups that face constant exposure to artificial light during hours when the body expects darkness. His work extends beyond simple sleep problems: he’s investigating how light pollution might be contributing to depression, anxiety, and metabolic disorders.

Working night shifts can be especially harmful for nurses who are exposed to bright hospital lighting as well as artificial light from screens. (© LIGHTFIELD STUDIOS – stock.adobe.com) Why Your Brain Expects Darkness

Humans evolved over millions of years with predictable cycles of light and darkness. Our brains contain what scientists call a “master clock.” It’s a small cluster of cells that coordinates when hormones are released, when body temperature changes, and when different organs become active or inactive.

When artificial light hits our eyes during nighttime hours, it confuses this internal timing system. The brain receives mixed signals about what time it is, disrupting the natural rhythm that governs nearly every biological process in the body.

Nelson’s laboratory work focuses on measuring how this disruption affects the brain and body. His studies examine changes in immune function, inflammation levels, and the production of hormones that regulate mood, hunger, and stress response.

Encouraging earlier bedtimes and healthy sleep patterns is especially important for still-developing brains. (Syda Productions/Shutterstock) Shift Workers Face the Greatest Risk

Nearly 15% of American workers — including nurses, factory workers, security guards, and others — work non-traditional hours that put them in chronic conflict with their natural body clocks. Nelson’s research shows this group faces elevated risks for health problems that extend far beyond feeling tired.

The biological effects are measurable. When people are exposed to light during natural sleeping hours, their bodies show changes in how they process blood sugar, potentially increasing diabetes risk. The disruption also affects hormones that control hunger and feelings of fullness, which may explain higher obesity rates among shift workers.

Brain inflammation, a factor linked to depression and anxiety, also increases when circadian rhythms are disrupted. Stress hormones that normally follow predictable daily patterns become erratic, affecting everything from blood sugar control to immune system function.

Testing Real-World Solutions

Nelson is currently conducting trials that could change how hospitals and workplaces approach lighting. “We have two clinical trials in which we are examining the role of blocking the disruptive effects of light at night on clinical outcomes after stroke and cardiac surgery in the intensive care units,” he explains.

The trials also test bright blue light devices designed to help reset night shift nurses’ body clocks, potentially improving their sleep, thinking abilities, and mood.

These studies represent an important step toward applying laboratory discoveries to real-world medical care. Success could lead to new hospital policies and better support systems for the millions of Americans who work overnight shifts.

Simple changes might make a difference: using amber or red lights in evening hours, installing blackout curtains, and designing workplaces that consider natural body rhythms rather than fighting against them.

Dr. Randy J. Nelson (Credit: WVU Rockefeller Neuroscience Institute) The Time-of-Day Factor

Nelson advocates for something that might seem minor but could have major implications: requiring scientists to report what time of day they conduct experiments. “The answer to an experimental question may depend in part on the time-of-day when the question is asked,” he notes.

Currently, most research papers don’t include this information, even though body rhythms can significantly influence experimental results. This oversight could be affecting the reliability of scientific studies across many fields.

For shift workers, potential solutions include specialized light therapy, strategic timing of sleep aids like melatonin, and workplace policies that acknowledge biological realities. Some companies have begun installing “circadian lighting” systems that automatically adjust light color and intensity throughout the day to match natural patterns.

The research even raises broader questions about how modern society is structured. Should cities consider the health impacts of street lighting? Could building codes support natural sleep-wake cycles? Should families rethink how much lighting to use in the house after sunset?

Nelson’s research represents a growing field of study examining how modern environments affect human biology. As his clinical trials progress and more scientists recognize the importance of circadian timing in research, we may see new approaches to everything from hospital design to workplace policies. The challenge now is translating these scientific insights into practical changes that can help millions of people living and working in our 24/7 world.

Disclaimer: This article is based on an interview with Dr. Randy J. Nelson published in Brain Medicine. The clinical trials discussed are ongoing and results have not yet been published in peer-reviewed form. This report does not constitute medical advice. Always consult qualified health professionals for medical care related to sleep, mood, or shift work.

Paper Summary Methodology

This article is based on an extensive interview with Dr. Randy Nelson, a circadian rhythm researcher at West Virginia University, published in Brain Medicine journal. Nelson’s research combines laboratory studies using animal models with clinical trials in humans. His laboratory measures immune function, neuroinflammation, metabolism, sleep patterns, and mood changes in response to disrupted light-dark cycles. Current clinical trials examine whether blocking disruptive light in intensive care units improves patient outcomes and whether light therapy devices can help reset night shift nurses’ circadian rhythms.

Results

Nelson’s research demonstrates that artificial light exposure at night disrupts circadian rhythms and causes measurable changes in brain function and behavior. His studies show increased neuroinflammation, altered immune function, disrupted metabolism, and mood changes. The research indicates that circadian disruption affects stress hormone production, glucose metabolism, and hunger-regulating hormones. Clinical trials are ongoing to test whether interventions can improve outcomes for medical patients and shift workers.

Limitations

The interview format means specific details about sample sizes, statistical significance, and experimental controls are not provided. Nelson references “nearly 500 papers” published during his career, but the interview doesn’t detail individual study methodologies or limitations. The clinical trials mentioned are ongoing, so results are not yet available. The research focuses primarily on shift workers and hospitalized patients, which may limit broader applicability.

Funding and Disclosures

The research is supported by NIH grant R21CA276027 and NSF grant 2242771. Nelson is also Co-Investigator on an NSF Track 1 award called “West Virginia Network for Functional Neuroscience and Transcriptomics.” The author affirmed that the interview content was free from conflicts of interest.

Publication Information

Source: Nelson, Randy J. “Disruption of circadian rhythms on brain function and health.” Brain Medicine, Genomic Press Interview. Published July 8, 2025. DOI: https://doi.org/10.61373/bm025k.0083. Interview conducted May 30, 2025, in Morgantown, West Virginia.