Nikhil Prasad Fact checked by:Thailand Medical News Team Jun 27, 2026 1 hour, 29 minutes ago
Medical News: A new study suggests that exposure to dim blue light during the night could do far more than disturb sleep. Researchers have found that it may also damage the body's immune defenses by triggering inflammation, oxidative stress, and harmful hormonal changes that affect the spleen, one of the body's most important immune organs.
New research shows that dim blue light at night may trigger inflammation and weaken the body's immune
defenses through stress hormone signaling
The research was conducted by scientists from the State Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University in Beijing, China. Using mice fed a high-fat diet to mimic modern lifestyles, the team discovered that blue light had far more damaging effects than dim white, green, or red light.
Blue Light Had the Strongest Harmful Effects
Artificial light at night has become almost unavoidable due to smartphones, tablets, LED lighting, televisions, and electronic displays. While previous studies have linked nighttime light exposure to sleep problems and metabolic disorders, this latest research investigated what happens to the immune system after prolonged exposure.
The researchers exposed mice to low-intensity colored light during the night for 12 weeks. Surprisingly, dim blue light produced the most severe biological changes, while green and red light caused little or no significant immune damage.
The mice exposed to blue light developed noticeably smaller spleens, indicating shrinkage of the organ. Microscopic examination also revealed severe deterioration of the spleen's white pulp, the region responsible for producing and activating immune cells. At the same time, the ability of spleen cells to multiply and respond to immune stimulation dropped dramatically, suggesting that the body's ability to fight infections had become impaired.
Oxidative Stress and Inflammation Increased
Further testing showed that blue light exposure created an unhealthy environment inside the spleen.
The researchers found significantly higher levels of oxidative stress, a process in which harmful molecules known as free radicals overwhelm the body's natural antioxidant defenses. Levels of malondialdehyde, a marker of cellular damage, increased substantially, while protective antioxidant enzymes including superoxide dismutase, catalase, glutathione peroxidase and total antioxidant capacity all declined sharply.
At the same time, inflammatory chemicals including IL-6, TNF-alpha and IL-1 beta increased, while protective immune-regulating molecules such as IL-10 and IL-5 fell considerably. This combination created an inflammatory state that could potentially reduce the body's ability to maintain healthy immune responses.
In addition, the researchers observed greater activation of genes linked to cell death while protective cell survival signals declined, explaining why immune tissues gradually became damaged.
Hormone Changes Appeared to Drive the Damage
One of the
study's most important discoveries involved corticosterone, a stress hormone similar to cortisol in humans.
Blue light exposure increased circulating corticosterone levels and also boosted activity of glucocorticoid receptors inside the spleen. These hormonal changes activated the NF-κB inflammatory pathway while suppressing the protective Nrf2/HO-1 antioxidant system, producing a double hit that promoted inflammation while reducing the organ's ability to defend itself against oxidative injury.
In this
Medical News report, these findings suggest that nighttime blue light may influence immunity through complex communication between the brain, stress hormones and immune organs rather than simply disrupting sleep.
The researchers also performed genetic analyses and found widespread changes in hundreds of genes involved in inflammation, immune regulation and antioxidant defenses, strengthening the evidence that blue light triggers extensive biological changes throughout the spleen.
Blocking the Stress Pathway Reduced the Damage
To determine whether stress hormones were responsible, the team treated another group of mice with metyrapone, which blocks corticosterone production, or RU486, which blocks glucocorticoid receptors.
Both treatments partially reversed the harmful effects. Spleen size improved, antioxidant activity recovered, inflammatory markers declined, immune cell growth increased, and the normal structure of the spleen began to return. Although the damage was not completely eliminated, these improvements strongly suggest that stress hormone signaling plays a major role in blue light-induced immune dysfunction.
Conclusion
The findings provide compelling evidence that even low-intensity blue light at night may have important biological consequences beyond sleep disruption, particularly when combined with unhealthy dietary habits. While this study was conducted in mice and additional human studies are needed, the results raise growing concerns about prolonged exposure to blue light from electronic devices and LED lighting during nighttime hours. The research also identifies stress hormone signaling as a possible therapeutic target to reduce some of the harmful immune effects associated with chronic nighttime blue light exposure.
The study findings were published in the peer reviewed journal: Antioxidants.
https://www.mdpi.com/2076-3921/15/7/800
For the latest research on the health effects of blue light, keep on logging to Thailand
Medical News.
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