Natural Light Exposure May Enhance Blood Sugar Control for Diabetes

Research suggests that spending time in natural light may positively impact blood sugar regulation for individuals with type 2 diabetes. A study led by Joris Hoeks at Maastricht University in the Netherlands indicates that exposure to sunlight can help enhance the body’s insulin response, which is crucial for maintaining healthy blood sugar levels.

Human cells and tissues operate on circadian rhythms, 24-hour cycles that help regulate metabolic functions, including blood sugar control. Prior research has shown that exposure to artificial light at night can disrupt these rhythms, leading to increased blood sugar levels. In contrast, spending more time in natural light appears to improve insulin sensitivity, which is vital for people managing diabetes.

To explore the effects of natural light, Hoeks and his team conducted a study involving 13 participants with type 2 diabetes, who had an average age of 70. The participants spent 4.5 days in a room with large windows, receiving natural light from 08:00 to 17:00. During this period, they continued taking their regular diabetes medications and engaged in light activities at their desks, which were equipped with devices set to low brightness.

In the evenings, participants were exposed to dim artificial light and had access to their devices until 23:00, before sleeping in complete darkness until 07:00. They consumed three standardized meals each day, designed to maintain their weight, and followed a fixed exercise routine throughout the study duration.

A parallel experiment was conducted under controlled conditions where the same participants spent time in windowless rooms illuminated solely by artificial light. This session took place either a month before or after the natural-light exposure period. Throughout both studies, participants wore continuous glucose monitors to track their blood sugar levels, although technical issues meant data was only available for ten participants.

The findings revealed that during the natural-light phase, participants maintained blood sugar levels within a healthy range 50 percent of the time. In contrast, this was achieved only 43 percent of the time during the artificial light experiment. The researchers defined a healthy blood sugar range as between 4.4 to 7.2 millimoles per litre, aligning with guidelines from the UK’s National Health Service and the US Centers for Disease Control and Prevention.

While the differences in percentages may appear minor, consistent exposure to unhealthy blood sugar levels can significantly increase the risk of complications associated with diabetes, such as heart disease. Hoeks emphasizes the potential benefits of natural light exposure, noting that light-sensitive cells in the eye play a vital role in regulating metabolic activity and are particularly responsive to the shorter wavelengths found in natural sunlight.

Further research is required to validate these findings and to determine whether individuals with type 1 diabetes or those classified as prediabetic would experience similar benefits. Glen Jeffery from University College London underscores the need for larger studies to confirm the results. He notes that awareness of the importance of daylight for health is gradually growing.

For individuals with type 2 diabetes, the implications of this study are clear: increasing exposure to natural light, even by simply sitting by a window, could provide a low-cost, accessible strategy for better blood sugar management. “It’s easy, accessible at no cost and available to everyone,” Hoeks concludes.