Back-lit devices slow melatonin, reduce sleep - a study

Using back-lit e-readers at bedtime can slow or prevent the production of the sleep hormone melatonin according to research by a team at Harvard Medical School published in the journal Proceedings of the National Academy of Sciences. The study conducted over two weeks saw twelve people spend five days reading from a paperback book and five days from an iPad. The experiment found that it took longer for participants to fall asleep with the back-lit e-reader, which uses blue light, the wavelength common in tablets, smartphones and LED lighting.


Blood samples showed the production of melatonin was reduced by reading an e-book. People took longer to fall asleep, slept less and were more tired the next morning, as their circadian clocks were disturbed. “The light emitted by most e-readers is shining directly into the eyes of the reader, whereas from a printed book or the original Kindle, the reader is only exposed to reflected light from the pages of the book,” lead researcher Professor Charles Czeisler told the BBC.


Source: telecompaper

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