A new scientific study has found that spending time in natural daylight can help people with type 2 diabetes control their blood sugar better and improve how their bodies use energy. The research was published in Cell Metabolism and shows a surprising connection between daylight exposure and metabolic health.
Most people in modern societies spend the majority of their day indoors under artificial light. This means they get much less exposure to natural sunlight, which our bodies use to set the internal circadian rhythm—a 24-hour biological clock that affects sleep, hormones, digestion, and metabolism. When this clock is out of sync, it can make problems like type 2 diabetes worse.
To study this, researchers invited 13 adults with type 2 diabetes to take part in a controlled experiment. Each person spent two periods of 4.5 days in a specially prepared office space. In one period, they worked in daylight shining through large windows. In the other period, the windows were covered and only artificial lights were used. During both stays, everyone ate the same meals, followed the same daily schedule, and continued their usual diabetes medications.
The results showed that natural daylight helped people keep their blood sugar in a normal range more often than under artificial light. Even though average glucose levels were similar in both conditions, daylight exposure reduced the number of sharp rises and falls. This matters because big swings in blood sugar can harm health over time.
The study also looked at how the body used energy. When in daylight, participants burned more fat for energy and relied less on carbohydrates. Muscle samples taken from volunteers showed that genes linked to the body’s internal clock were more synchronized to the time of day with daylight exposure. This suggests that sunlight may help reset the cells’ timing systems, improving how nutrients are processed.
Although the study involved only a small group of people, the findings are promising. They suggest that something as simple as spending more time in daylight each day could support metabolic health in people with type 2 diabetes. Natural light may become another helpful tool—alongside diet, exercise, and medication—in managing blood sugar and improving overall health.
Editor of Daily 27.
Predoctoral researcher at the Department of Sociology in University of Barcelona.