In a large-scale study involving 85,000 participants, scientists at Flinders University have discovered that night-time exposure to light significantly increases the risk of developing type 2 diabetes, regardless of daytime activities.
“Light exposure at night can disrupt our circadian rhythms, leading to changes in insulin secretion and glucose metabolism,” explained senior author Andrew Phillips, an associate professor from the College of Medicine and Public Health. “These disruptions affect the body’s ability to regulate blood sugar levels, which can ultimately lead to the development of type 2 diabetes.”
Using data from the UK Biobank, the study assessed 84,790 participants who wore wrist light sensors for a week between 2013 and 2016, and followed up nine years later. Analyzing 13 million hours of light-sensor data, researchers found a 67% greater risk of developing diabetes later in life. The study also noted that the risk increased with the amount of time spent exposed to light, independent of daytime behaviors.
The data supports the hypothesis that light exposure at night, which suppresses or shifts central circadian rhythms, may alter insulin secretion and glucose metabolism.
“For instance, disrupted circadian melatonin or glucocorticoid rhythms may exhibit elevated concentrations during waking hours, thereby reducing pancreatic insulin secretion and promoting hepatic glucose production at times that coincide with food intake,” the researchers noted. “Persistent circadian misalignment may lead to consistently elevated postprandial glucose levels, increasing the size and inflammation of adipocytes, promoting insulin resistance, and secreting inflammatory markers like interleukin-1β that inhibit pancreatic beta-cell function.”
While factors such as lifestyle and behaviors like shift work and irregular sleeping patterns impact diabetes risk, the researchers accounted for these variables and still found that light exposure between 12:30 am and 6 am posed a significant health risk. They suggest that limiting personal light exposure during these hours can help maintain circadian rhythms and potentially lower the risk of developing type 2 diabetes.
“The results showed that exposure to brighter light at night is associated with a higher risk of developing diabetes, with a dose-dependent relationship between light exposure and risk,” said Phillips. “Our findings suggest that reducing your light exposure at night and maintaining a dark environment may be a simple and cost-effective way to prevent or delay the development of diabetes.”
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