New research suggests that blue light in the evening may have an adverse effect on how glucose is metabolized by the body.

The prevalence of diabetes and other metabolic disease has been steadily increasing in the past few decades. Around half of adults in the United States have diabetes or its precursor pre-diabetes and numbers continue to rise. This disease affects millions of people worldwide. Could this be partially due to an increase in blue light in our environment? A new study looked at the way blue light affects our metabolism and have found a possible link.

Blue Light and Melatonin

Humans are designed to be awake when it is light and asleep for most of the dark hours. When our retinas sense low light levels, they pass a message to the suprachiasmatic nucleus of the hypothalamus. The SCN then tells the pineal gland to produce melatonin, which is the hormone that cues sleep as well as the metabolic activities that occur during sleep. This melatonin is not made in as high of levels when we are exposed to light, particularly blue light. There is a very good chance that blue light, which is the predominant light in electrical devices, is literally keeping us up at night. But what does this have to do with metabolism?

How Does Light Affect Your Metabolism?

New research suggests that the bright blue light filling our world may make our metabolisms more sluggish, contributing to insulin resistance and eventually diabetes. Adult volunteers were exposed to blue-enriched light at different times of the day and were asked to eat while undergoing this light exposure. People who were exposed to bright light while eating in the evening showed higher glucose levels, more insulin resistance and slower metabolism of their meals. This confirms previous studies of the relationship between light and metabolism, which found that people who get most of their light exposure in the morning have faster metabolisms. Ivy Cheung, the neurological researcher who headed this study, commented,

“Our findings show that insulin was unable to acutely bring glucose levels back to a baseline level following a meal with bright light exposure in the evening. The results of this study emphasize that our lighting environment impacts our health outcomes.”

People who eat in the evening while being exposed to high levels of blue light have higher blood glucose and less insulin response. Over time, this sluggish metabolism will make people heavier, but there are even more serious effects. Consistently high blood glucose can eventually contribute to type 2 diabetes and other serious illnesses.

Can Lighting Affect Your Waistline?

While the subject will need to be further studies, there are a few powerful implications for public health. In theory, people may be able to stimulate their metabolism and decrease health risk simply by modifying light levels in their environments. Diabetics may be able to control their disease more tightly by controlling light exposure, preventing some of the complications of uncontrolled diabetes.

In addition, this connection between bright light and slow metabolism may explain why time-restricted feeding appears to improve both metabolic activity and general health. People who are eating when their metabolisms are highest and avoiding food at times of lower insulin activity will naturally be able to lose weight more quickly.

Research seems to indicate that when you eat and the conditions of your environment may matter just as much as your choice in foods and the calorie count. If something as simple and easy to control as light levels is behind the recent upswing in metabolic disease, people may be able to lower their weight and their disease risk with a few simple changes. This is great news for those who struggle with pre-diabetes or diabetes, as well as the general public health.