Study Shows How Exposure to Natural Daylight Can Help Diabetics

NEW DELHI — Daylight can help improve metabolic health, enabling people with type 2 diabetes to achieve better glycaemic control, according to a study.

Researchers from the University of Geneva (UNIGE) in Switzerland and Maastricht University in the Netherlands found that people exposed to natural light had blood glucose levels in the normal range for more hours per day, with less variability.

In addition, their melatonin level -- the sleep hormone -- was a little higher in the evening, and fat oxidative metabolism was also improved.

The study, published in the journal Cell Metabolism, provided the first evidence of the beneficial impact of natural light on people with this condition.

"It has been known for several years that the disruption of circadian rhythms plays a major role in the development of metabolic disorders that affect an increasing proportion of the Western population," said Charna Dibner, associate professor at the UNIGE.

For the study, the team recruited 13 volunteers aged 65 and over, all with type 2 diabetes.

They spent 4.5 days in specially designed living spaces, lit either with natural light through large windows or with artificial light. After a break of at least four weeks, they returned for a second session, this time in the other light environment.

To better understand the observed positive changes in the body's metabolism, the scientists took blood and muscle samples from the volunteers before, during, and after each light treatment.

They analysed the regulation of molecular clocks in cultured skeletal muscle cells together with lipids, metabolites, and gene transcripts in the blood.

Together, the results clearly show that the internal clock and metabolism are influenced by natural light.

"This could be the reason for the improved blood sugar regulation and the improved coordination between the central clock in the brain and the clocks in the organs," Dibner explained.