A guest contributor, Jim Rollince, shares this informative article on how the amount of light in our environment can have a big impact on health.

Jim writes:

Ambient Light During Sleep and The Affect on Metabolism

By Jim Rollince of Gym Source, distributor of home gym equipment, including treadmills, ellipticals and other home gyms.

Frustrated that your exercise routine and constantly calorie counting has not yielded any weight loss results? Are you in fact gaining more weight then before you began exercising and monitoring your food consumption? The key to your weight gain could be a result of an external factor that you never took into account, the exposure to light at night.

New research in sleep science has shown that prolonged exposure to light during the regular nighttime sleeping hours may cause weight gain. This weight gain occurs independent of daytime calorie consumption and physical activity.

These research findings came out of a study by the Proceedings of the National Academy of Sciences. The study tested animals, and the findings have begun to raise discussion from the scientific community based on whether the human body experiences metabolic sluggishness and weight gain as a result of too much light exposure at night.

A research team from Ohio State University discovered that mice exposed to a dim light during the course of a night for roughly a two-month period, gained 50 percent more body mass than mice exposed to a regular light-dark cycle. “Although there were no differences in activity levels or daily consumption of food, the mice that lived with light at night were getting fatter than the others,” said Laura Fonken, a neuroscience doctoral student at Ohio State and director of the study.

Although the lab mice were exposed to nighttime light they did not become less active nor eat more. However, they did eat at times when they normally wouldn’t. In fact, in one part of the study when the mice were exposed to light at night and then restricted from eating with the exception of their normal feeding times, they did not experience more weight gain.

“Something about light at night was making the mice in our study want to eat at the wrong times to properly metabolize their food,” Randy Nelson, professor of neuroscience and psychology at Ohio State and co-author of the study.

The researchers found that levels of the stress hormone corticosterone were not different among the mice exposed to the dim light and mice exposed to standard light-dark. This finding was surprising for the research team since corticosterone is connected to changes in metabolism. The research has shown that changes in metabolism have the potential to cause weight gain independent of corticosterone levels.

What is the link between dim light at night and fat-causing changes in one’s metabolism? The Ohio State research team postulates that the presence of light during the night works to disrupt hormone melatonin. Hormone melatonin plays a significant role in the functioning of the metabolism. To this end, light exposure at night could in fact disrupt expression of clock genes, which aid in controlling the time animals choose to be active and eat.

Dr. Nelson furthers her comments by saying that if her team’s research results are confirmed, eating late at night is a serious contributing factor to obesity. “Light at night is an environmental factor that may be contributing to the obesity epidemic in ways that people don’t expect,” he said. “Societal obesity is correlated with a number of factors including the extent of light exposure at night.”

Past research similar to this study have been prolonged television and computer use as contributing risk factors for obesity. Yet these studies were centered in the idea that engaging in prolonged television or computer usage contributed to a lack of physical activity. The current connection between weight gain and the light coming from a TV or computer, is related to the disruption of the metabolism via the negative bodily effects of getting too much light exposure at night and eating at the wrong time.

“Clearly, maintaining body weight requires keeping caloric intake low and physical activity high, but this environmental factor may explain why some people who maintain good energy balance still gain weight,” Dr. Nelson’s press statement.