Researchers from Maastricht University have identified that exposure to natural light may support both the treatment and prevention of type 2 diabetes. The study was presented at the annual meeting of the European Association for the Study of Diabetes in Hamburg.
The experiment enrolled 13 adults diagnosed with type 2 diabetes, with an average age around 70. Participants stayed under tightly controlled conditions in research facilities to precisely monitor light exposure, diet, and activity levels throughout the study period.
During the daylight phase, participants received natural daylight through windows from 8 a.m. to 5 p.m. Evenings were kept dim, and during the sleep window from 11 p.m. to 7 a.m., they remained in darkness. This setup lasted 4.5 days. After a four-week interval, the protocol was reversed for a follow-up period in which participants spent the daytime hours under artificial light, while evenings and nights followed the same dim and dark regimen as before.
Blood glucose levels stayed within the normal range, defined here as roughly 4.4 to 7.8 mmol/L, for a greater portion of time during natural daylight exposure than during artificial lighting. Specifically, natural daylight accounted for about 59 percent of the 4.5-day period, compared with 51 percent during artificial light. The study also observed higher activity of the circadian-regulating genes Per1 and Cry1 under natural light, suggesting a stronger alignment of circadian rhythms with the natural day-night cycle.
The findings point to improved metabolic control associated with natural daylight exposure, implying that daylight could play a beneficial role in managing metabolism. This has potential implications for strategies aimed at treating and preventing type 2 diabetes and related metabolic conditions such as obesity.
In discussing these results, researchers noted that similar light-related effects have been observed in other contexts. While daylight exposure shows promise for metabolic health, further studies are needed to understand the broader physiological mechanisms and to determine how these findings translate into practical recommendations for diverse populations. (Attribution: Maastricht University research team; European Association for the Study of Diabetes proceedings.)