Artificial Nighttime Light Harms Rodent Immunity, Study Finds

A groundbreaking study from Tel Aviv University reveals a concerning link between artificial nighttime lighting (ALAN) and compromised immune systems in wild rodents, suggesting that our increasingly illuminated nights may pose a greater danger than previously understood. The research, published in the journal Environmental Pollution, is the first to establish a direct connection between ALAN and weakened immunity in mammals.

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Even minimal artificial light at night (ALAN) – at intensities equivalent to standard street lighting – disrupts the natural immune rhythms of wild rodents, leading to a 2.35-fold increase in mortality, according to a first-ever study at Tel Aviv University.

Conducted on two species of local rodents, the golden spiny mouse and the common spiny mouse, the study found that even minimal exposure to artificial light at intensities comparable to standard street lighting disrupted natural immune rhythms. This disruption resulted in a staggering 2.35-fold increase in mortality among the exposed animals. The findings are particularly alarming given that both species inhabit the Israeli desert and are accustomed to natural light cycles.

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Their research is the first in the world to prove the connection between ALAN and weakened immunity in mammals.

Professor Noga Kronfeld-Schor, a lead researcher on the study, emphasized that ALAN is a form of pollution that, unlike others, can be relatively easily managed. She urged municipalities and public buildings to reduce nighttime illumination, advocating for a return to darkness not only for the benefit of wildlife but also for human health. "Children are not afraid to go to sleep in the dark," she noted, suggesting that a natural darkness is conducive to a stronger immune system for all.

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compared to other types of pollution, ALAN is relatively easier to deal with – if municipalities and various public buildings agree to turn down the lights at night.

This research adds to a growing body of evidence highlighting the ecological impact of human activity. While previous studies have focused on noise pollution, this work directly implicates light pollution in disrupting fundamental biological processes. The implications extend beyond wildlife, raising questions about the long-term effects of ALAN on human health, particularly concerning immune function and sleep patterns. The study serves as a critical call to action for more responsible lighting practices in our urban and natural environments.

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She urged that not only non-human animals but also children and adults go to sleep at night in darkness, without a night light, as “illumination that is not moonlight weakens the immune system. Children are not afraid to go to sleep in the dark,” she insisted.