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November 1, 2024
An alarming study from Flinders University, South Australia, has shed new light on the impact of night-time illumination on health, revealing a correlation between bright nights, reduced daytime exposure to sunlight, and an increased risk of mortality. This large-scale research, examining over 13 million hours of light exposure data from 89,000 individuals, highlights the profound effects of artificial light exposure at night on the body’s internal clock, or circadian rhythm, and its implications for overall health and longevity.
The findings, published on Thursday, revealed that individuals subjected to high levels of artificial light at night faced a 21-34 percent higher risk of death. Conversely, those who experienced more daylight exposure showed a 17-34 percent reduction in their mortality risk. This link, say researchers, stems from disruptions to the body’s circadian rhythm, which is finely tuned to the natural cycle of day and night.
The circadian rhythm orchestrates numerous physiological processes within the body over a 24-hour period. Lead researcher and sleep expert Dr. Sean Cain emphasized that disturbances to this rhythm, such as exposure to bright artificial lights at night, can trigger a range of adverse health conditions, including diabetes, obesity, cardiovascular disease, mental health issues, and, ultimately, higher mortality risk. “Exposure to brighter nights and darker days can disrupt our circadian rhythms,” Cain noted in a press release. “This disruption is known to lead to various health issues that could increase the risk of death.”
Dr. Daniel Windred, the lead author, stressed the importance of maintaining an environment that supports natural circadian rhythms, particularly by reducing nighttime light exposure and maximizing daytime brightness. “The study underscores the importance of seeking bright light during the day to enhance circadian rhythms, while preserving a dark environment across the late night,” Windred explained.
The study utilized data from the UK Biobank, examining 89,000 participants aged 40-69 who wore light sensors on their wrist under natural conditions for a week between 2013 and 2016. Mortality rates among these participants were tracked over an eight-year period through records maintained by the National Health Service. This extensive analysis provides new insights into the far-reaching effects of artificial lighting on public health, supporting recommendations for strategies to mitigate the risks of circadian disruption.
For individuals and public health policymakers, these findings underscore the need to reassess the impacts of urban lighting and personal light exposure habits. The implications could drive changes in workplace and home lighting environments, encouraging light management practices that could significantly contribute to reducing preventable health risks.
