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When the night never ends: Study links artificial light exposure to accelerated dementia symptoms

‘From night-shift workers and late-night students to anyone scrolling endlessly through their phones, many of us are now living under near-constant artificial light’.

4 min readUpdated: Oct 10, 2025 08:42 PM IST

Managing circadian rhythms could significantly delay or reduce the impact of Alzheimer’s and Parkinson’s disease.

Artificial light and sleep disruption can worsen age-related neurodegeneration, according to a Delhi University study. (File)

“Protecting our natural circadian rhythm could be one of the simplest yet most effective ways to reduce long-term brain damage. It reminds us that something as ordinary as light, when misused, can have extraordinary consequences for our mental health” — Prof Surajit Sarkar, department of genetics, DU’s South Campus

A study by researchers at Delhi University (DU) shows how light pollution disrupts sleep and speeds up neurodegeneration.

“For the first time we have demonstrated that sleep deprivation due to factors like increased light pollution or other lifestyle disruptions can lead to an earlier and more severe development of age-onset brain diseases such as Alzheimer’s and Parkinson’s,” Prof Surajit Sarkar, department of genetics at DU’s South Campus, told The Indian Express.

Findings of the study have been published in the international neuroscience journal ‘Neurochemistry International’. Prof Sarkar said their findings suggest managing sleep properly could significantly delay or reduce the impact of these debilitating diseases, highlighting the importance of sleep for brain health.

Dementia and other age-related brain disorders have become a major global health challenge with Alzheimer’s disease alone responsible for over three-quarters of all cases among older adults worldwide. In India, the number of people living with dementia is expected to surge to around 14.3 million by 2050, according to studies.

Characterised by symptoms such as memory loss, confusion, social withdrawal and difficulty performing everyday tasks, neurodegenerative disorders result from the irreversible loss of neurons in the brain.

The study found that disrupted sleep, triggered by continuous exposure to artificial light or “light pollution”, can hasten the early onset and worsen the severity of dementia-related symptoms.

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According to Prof Sarkar, these findings shed new light on how modern lifestyles, especially in brightly lit urban environments, may be quietly undermining brain health.

“Light is much more than just a signal for day and night,” the researchers said. “It plays a vital role in maintaining the brain’s internal rhythms.”

But in today’s world, where city lights never dim and screens glow late into the night, the brain’s delicate balance is being disrupted. This constant exposure to artificial illumination, they warn, is taking a hidden toll, particularly on people already vulnerable to neurodegenerative conditions such as Alzheimer’s and Parkinson’s disease.

In their study, researchers Prerna Aggarwal, Virender and Prof Sarkar used genetically engineered fruit flies (Drosophila melanogaster) carrying the human form of the toxic tau protein, a hallmark of Alzheimer’s disease. The team discovered that when these flies were exposed to continuous artificial light, disrupting their normal sleep patterns, their brain cells degenerated much faster. The flies showed early signs of movement difficulties and clear structural damage in brain regions that control memory, learning and sleep.

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Researchers found that unhealthy light exposure acted like an accelerator pedal for tau-related disease. It significantly increased the stickiness of the tau protein, promoting the formation of large, toxic clumps that choke neurons at a much faster rate. Although abnormal light exposure has long been linked to disrupted circadian rhythms and disturbed sleep-wake cycles, the latest study points to its possible role in worsening the molecular and cellular changes that drive neurodegeneration.

The researchers, however, said more research is needed to fully understand how light pollution intensifies disease progression at the cellular level. “From night-shift workers and late-night students to anyone scrolling endlessly through their phones, many of us are now living under near-constant artificial light,” Prof Sarkar cautioned.

Anuradha Mascarenhas

Anuradha Mascarenhas is a Senior Editor at The Indian Express, based in Pune. With a career spanning three decades, she is one of the most respected voices in Indian journalism regarding healthcare, science and environment and research developments. She also takes a keen interest in covering women's issues . Professional Background Education: A gold medalist in Communication and Journalism from Savitribai Phule Pune University and a Master’s degree in Literature. Author: She authored the biography At The Wheel Of Research, which chronicles the life and work of Dr. Soumya Swaminathan, the former Chief Scientist at the WHO. Key Focus: She combines scientific accuracy with storytelling, translating complex medical research into compelling public and human-interest narratives. Awards and Recognition Anuradha has won several awards including the Press Council of India's national award for excellence in journalism under the gender based reporting category in 2019 and the Laadli Media award (gender sensitivity -2024). A recipient of the Lokmat journalism award (gender category-2022), she was also shortlisted for the RedInk awards for excellence in journalism-2021. Her debut book At The Wheel Of Research, an exclusive biography of Dr Soumya Swaminathan the inaugural chief scientist of World Health Organisation was also nominated in the Popular Choice Category of JK Paper AUTHER awards. She has also secured competitive fellowships including the Laadli Media Fellowship (2022), the Survivors Against TB – New Research in TB Media Fellowship (2023) and is part of the prestigious 2025 India Cohort of the WomenLift Health Leadership Journey.” Recent Notable Articles (Late 2025) 1. Cancer & Specialized Medical Care "Tata Memorial finds way to kill drug-resistant cancer cells" (Nov 26, 2025): Reporting on a breakthrough for triple-negative breast cancer, one of the most aggressive forms of the disease. Discipline, diet and purpose; How a 97-year-old professor defies ageing'' (Nov 15, 2025) Report about Prof Gururaj Mutalik, the first Head of Department at Pune's B J Government Medical College who at 97 credits his longevity to healthy habits and a strong sense of purpose. 2. Environmental Health (The "Breathless Pune" Series) Long-term exposure even to 'moderate' air leads to chronic heart, lung, kidney issues" (Nov 26, 2025): Part of an investigative series highlighting that even "safe" pollution levels are damaging to vital organs. "For every 10 µg/m3 increase in PM2.5 level, there was 6-8% jump in medicine sales" (Nov 23, 2025): Using commercial data to prove the direct link between air quality and respiratory illnesses in Pune. 3. Lifestyle & Wellness News "They didn't let cancer, diabetes and heart disease stop them from travelling" (Dec 22, 2025): A collaborative piece featuring survivors who share practical tips for traveling with chronic conditions. At 17, his BP shot up to 200/120 mmHG; Lancet study flags why child and teen hypertension doubled between 2000 and 2020'' (Nov 12,2025)--A report that focusses on 17-year-old-boy's hypertensive crisis and reflects the rising global trend of high blood pressure among children and adolescents. 4. Scientific Recognition & Infrastructure For promoting sci-comm, gender diversity: IUCAA woman prof highlighted in Nature" (Nov 25, 2025): Covering the global recognition of Indian women scientists in gender studies and physics. Pune researchers find a spiral galaxy like the Milky Way from early universe'' (December 3, 2025)- A report on how Indian researchers discovered a massive galaxy that existed when the universe was just 1.5 billion years old , one of the earliest to have been observed so far. Signature Beat: Health, Science & Women in Leadership Anuradha is known for her COVID-19 reportage, where she was one of the first journalists to provide detailed insights into the Covishield and Covaxin trials. She has a dedicated interest in gender diversity in health and science, often profiling women researchers who are breaking the "leaky pipeline" in STEM fields. Her writing style is scrupulous, often featuring interviews with top-tier scientists and health experts from various institutions. ... Read More

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