Electric light exposure before bed may alter metabolic function, increase type 2 diabetes risk

Exposure to electric light in the hours just before going to bed may cause a disruption to the metabolic system that increases the risk of developing type 2 diabetes, according to a new report from Brigham and Women’s Hospital researchers.

The findings may be significant because many people in today’s society, whether for professional reasons or lifestyle choices, are exposed to light from computer monitors and televisions throughout the day and into the night. This may have serious implications for their metabolic function.

The researchers reported in the Journal of Clinical Endocrinology and Metabolism that exposure to light during the eight hours before sleep suppresses melatonin levels. This hormone plays an important role in many metabolic functions, including body temperature regulation, sleepiness, blood pressure levels and blood sugar regulation.



For the study, researchers examined the melatonin levels of two groups of participants. One was exposed to light for several hours before going to bed, while the other was not. This went on for five days. During this time, the researchers found that melatonin circulated at its peak for an average of 90 minutes less in the group that was exposed to light.



"Given that chronic light suppression of melatonin has been hypothesized to increase relative risk for some types of cancer and that melatonin receptor genes have been linked to type 2 diabetes, our findings could have important health implications for workers who are exposed to indoor light at night over the course of many years," said Joshua Gooley, the lead investigator.

He added that further research is needed to understand the process by which light affects melatonin levels, and how this in turn regulates blood sugar levels and type 2 diabetes risk. However, until this research is completed, individuals may benefit from avoiding unnecessary light exposure before going to bed.
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