Lack of blue-wavelength light may disrupt adolescent circadian rhythms.

The Los Angeles Times (2/17, Maugh) reports, “Riding in school buses in the early morning, then sitting in poorly lighted classrooms are the main reasons students have trouble getting to sleep at night,” according to a study published in the journal Neuroendocrinology Letters. That is because adolescents “need bright lights in the morning, particularly in the blue wavelengths, to synchronize their inner, circadian rhythms with nature’s cycles of day and night.” In fact, “if they are deprived of blue light during the morning, they go to sleep an average of six minutes later each night, until their bodies are completely out of sync with the school day.”

The AP (2/17, Neergaard) reports that for the study, 11 eighth-graders “donned special orange goggles that block short-wavelength ‘blue light,’ but not other wavelengths necessary for proper vision,” from the time they got up until the time school ended. “Blocking that light for five days upset the students’ internal body clocks — delaying by half an hour their evening surge of a hormone called melatonin that helps induce sleep, Rensselaer Polytechnic Institute researchers reported.”

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