Could different light levels affect your blood sugar and metabolism?

Biologically, our bodies are used to low light or darkness after sunset. Artificial light has changed this cycle of light in our lives.

Why is this important? Well, new research shows that not meeting the body’s need for light could have negative effects on metabolic health. Thus, the level of light exposure at different times of the day could affect our metabolism and blood sugar. Let’s find out more about this study.

How does the level of daylight affect our metabolism?

Nowadays, artificial light is constantly available around us. So most people are exposed to electric light and light-emitting screens throughout the day, including evenings and nights.

Exposure to light is closely linked to the regulation of our sleep cycle, activity and eating patterns, body temperature and metabolism.

Any disorders in these areas caused by exposure to more light than natural light are related to:

  • Sleep and circadian rhythm disturbances(source)
  • An increased risk of obesity(source)
  • Metabolic diseases(source)

Also, a study of 513 older people showed that an increase in ambient light levels during the evening resulted in up to a 51% increase in the risk of diabetes.

Could mimicking the natural cycle of light and dark improve our health?

A group of researchers at Maastricht University in the Netherlands conducted a study to find out whether indoor lighting that better mimics natural light and dark cycles would be better for the metabolism of people with high blood sugar.

What did this study consist of?

To test this, the researchers monitored 14 overweight people with high blood glucose levels, which could put them at increased risk of developing diabetes, for two 40-hour sessions in a controlled environment.

In one session, they were exposed to bright electric light from 8 a.m. to 6 p.m., then dim light from 6 p.m. to 11 p.m. and darkness all night. In the other session, the same people were exposed to dim light from 8am to 6pm and bright light from 6pm to 11pm.

So what were the results?

In this experiment, Dutch researchers found that a bright day followed by a dark evening had mostly positive effects. Under these conditions, participants had lower blood sugar levels before dinner and had a higher metabolism after dinner and overnight, meaning they burned more calories at those times.

Scientists also observed a greater difference in body temperature between day and night when humans were exposed to bright days followed by dark evenings. They noted that temperature difference is linked to blood pressure control – although the study didn’t look at this specifically, it’s possible that following more natural light patterns could help improve blood pressure as well.

Researchers said more research is needed on how lighting in indoor environments, including offices and homes, could be adapted to help people better control their metabolism and blood sugar levels.

How good was the research?

The small number of participants in the study – just 14 men and women, all overweight – means that, while the results are interesting, more studies are needed before firm conclusions can be drawn.

One positive aspect of the study was that the researchers tried to keep other conditions constant between the two sessions so that other factors would not interfere with the results. For example, meal times and what participants ate were kept the same between the two sessions. The room temperature was also maintained at the same levels and participants spent the same amount of time standing, sitting and exercising.

The study took place in rooms specifically designed to measure how much energy people burned, and participants wore smart devices on their wrists to monitor their sleep patterns.


Although researchers say they are “convinced” that light conditions contribute to the development of diabetes, more research is definitely needed.

In the meantime, good ways to keep your blood sugar under control and reduce your risk of developing type 2 diabetes include eating a healthy diet and maintaining an active lifestyle.

Keep in mind that no study can predict your future health. If you experience unpleasant symptoms, consult a specialist.


The Complex Effects of Light on Metabolism in Humans

The influence of bright and dim light on substrate metabolism, energy expenditure and thermoregulation in insulin-resistant individuals depends on time of day | Diabetologia

The effects of light at night on circadian clocks and metabolism

Association of Exposure to Artificial Light at Night While Sleeping With Risk of Obesity in Women

Duration of shiftwork related to body mass index and waist to hip ratio

Leave a comment