Sitting next to a window may help people with type 2 diabetes control their insulin levels, according to new research.
The study, published in Cell Metabolism, found that exposure to natural light — even indoors next to a window — changes how the body processes glucose and uses energy.
People in Western societies spend 80% to 90% of their time under artificial lights, which are much dimmer and less dynamic than sunlight, the researchers noted.
Natural daylight is a powerful cue for the body’s internal clock, also known as the circadian rhythm.
The body’s internal clock influences many processes, including digestion, hormone release and metabolism, according to research.
When it gets out of sync, it can worsen insulin resistance and blood sugar control, which are two of the main issues caused by type 2 diabetes.
To test the effects of daylight on blood sugar, scientists recruited 13 adults with type 2 diabetes.
Each person spent two separate 4.5-day periods in a controlled office setting, according to a press release.
In one period, they worked in front of large windows with natural daylight streaming in. In the other period, participants worked in the same room with the windows covered and were exposed only to typical indoor lighting.
Everyone ate similar meals, followed the same schedule and continued their usual diabetes medications in both conditions.
While average blood sugar levels didn’t differ drastically between the two conditions, people spent more time in the healthy glucose range when they were exposed to natural daylight — their blood sugar fluctuated less and stayed within a desirable range for a greater portion of the day.
Exposure to natural light also affected metabolism. In daylight, participants burned more fat and fewer carbohydrates for energy.
Muscle biopsies and laboratory tests further showed that the genes responsible for the body’s cellular clocks were more synchronized under natural light conditions, the study revealed.
Better alignment of these genes can improve nutrient processing and how cells respond to insulin, the researchers concluded.
However, daylight isn’t a replacement for medication or traditional management strategies like diet and exercise, according to the team.
The study did have some limitations, including that the group of patients was small. The researchers cautioned that larger studies are needed to confirm these results and determine how much natural light exposure is optimal.
“This study also highlights the often unnoticed impact of the built environment on our health, and raises further concerns about the prevalence of office environments with poor (natural) daylight access,” the researchers noted.
