A new study suggests that something as simple as sitting near a window and enjoying natural sunlight for a few hours each day might help people with type 2 diabetes manage their blood sugar levels.
The research, published in the journal Cell Metabolism, found that exposure to daylight helps the body maintain healthier glucose levels.
Natural daylight is already known to improve mood and support overall health. But many people today, especially in Western countries, spend most of their time indoors—up to 80% or 90% of the day—under artificial lights. These lights are not as bright or dynamic as natural sunlight.
This matters because our bodies work on internal 24-hour clocks, called circadian rhythms. These rhythms control many important processes, like digestion and body temperature.
They are regulated by light, especially natural light from the sun. When people don’t get enough sunlight, their circadian rhythms can become disrupted, which increases the risk of type 2 diabetes.
Previous research has shown that artificial lights at night can interfere with these rhythms and that going outside in the sunlight can improve how the body responds to insulin, the hormone that controls blood sugar. But until now, no one had tested how daylight coming through a window might affect people with diabetes.
To study this, researchers invited 13 people with type 2 diabetes to spend time in a special office setting. Each person spent two separate 4.5-day sessions in the same room.
In one session, they sat at a desk in front of large windows from morning until late afternoon, getting natural daylight. In the other session, the windows were covered, and they were only exposed to typical indoor office lighting.
During both sessions, participants ate the same meals at the same times, did the same physical activities, and continued taking their usual medications.
The results showed something surprising. While their average blood sugar levels were about the same during both sessions, participants spent more time in the healthy blood sugar range when they were exposed to natural daylight. Their bodies also used energy differently. In sunlight, they burned more fat and fewer carbohydrates.
The researchers went further and studied muscle samples from the volunteers. They also grew muscle cells in a lab.
They found that genes inside the muscle cells, which help control the body’s internal clocks, worked better when exposed to natural light. This means that sunlight helps keep the body’s systems running on time, improving how muscles use nutrients.
Even though the study had only 13 people, the findings are promising. They suggest that getting more natural daylight each day may be a simple and effective way to support other treatments for type 2 diabetes. Reducing blood sugar spikes and swings can improve quality of life and long-term health.
The scientists say their research shows that light—especially sunlight—is more powerful than we might think. Something as easy as sitting by a window for a few hours could help manage a serious condition like diabetes.
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