London: People who regularly stay awake till late night, either working or using social networks, are putting their health at risk.A new study of mice led by a Johns Hopkins biologist has revealed that exposure to bright light at night from lamps, computers and even iPads may cause depression and learning issues. “Basically, what we found is that chronic exposure to bright light -- even the kind of light you experience in your own living room at home or in the workplace at night if you are a shift worker -- elevates levels of a certain stress hormone in the body, which results in depression and lowers cognitive function,” said Samer Hattar, a biology professor in the Johns Hopkins University’s Krieger School of Arts and Sciences.The mice study demonstrates how special cells in the eye (called intrinsically photosensitive retinal ganglion cells, or ipRGCs) are activated by bright light, affecting the brain’s center for mood, memory and learning.Though the study was conducted on mice, Hattar says the effect may be similar in humans.“Mice and humans are actually very much alike in many ways, and one is that they have these ipRGCs in their eyes, which affect them the same way,” he said.“In addition, in this study, we make reference to previous studies on humans, which show that light does, indeed, impact the human brain’s limbic system. And the same pathways are in place in mice,” he noted.
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