In the study, thirteen participants spent two periods of four and a half days in a room at the Maastricht University Faculty of Health, Medicine and Life Sciences (FHML). They spent eight hours a day in an office setting. During one stay, the room was lit only by lamps. Four weeks later, during a second stay, it was lit by natural daylight coming in through the windows. The researchers made sure to keep other factors that can affect blood sugar levels – eating, sleeping and exercise – the same, allowing them to see the positive effect of daylight.
Demanding
Light helps to synchronise our biological clock with the natural day-night cycle, says researcher Joris Hoeks, an associate professor at FHML, to Observant. The biological clock controls our internal circadian rhythm. When it is in sync with the natural cycle, the body is better prepared to deal with external stimuli such as food. This helps it process sugar in the blood more effectively – the mechanism that is disrupted in people with diabetes. Daylight, Hoeks explains, is more effective in synchronising these rhythms than artificial light because it contains a broader spectrum of wavelengths. Special cells in the eye respond more strongly to this kind of light.
The researchers say they are the first to demonstrate this effect. Had no one thought of it before? “The idea itself is simple”, Hoeks agrees. “But carrying out the research is not. You have to control for factors such as food, sleep and exercise, recreate a normal working week, and ask volunteers to stay here day and night for that whole week – twice. That’s demanding.”
Free and freely accessible
Thirteen people is a small group, and for three participants not all data could be collected. “That’s a valid point”, admits Hoeks. “We acknowledge that ourselves. This study should be seen as a proof of concept, not one that should immediately inform clinical guidelines. The results now need to be confirmed in larger groups.” Still, he stresses: “In our study, the difference between daylight and artificial light was small, but measurable and consistent. Daylight is free and freely accessible, and getting more of it certainly wouldn’t hurt. I would recommend it to people with type 2 diabetes – preferably by going outdoors, so you also get some exercise.”