SHAFAQNA – Using an iPad before bedtime makes it harder to get to sleep, reduces alertness the next morning and could lead to far more serious illnesses. Researchers said glowing screens should be banished from the bedroom after finding that they put the body’s clock back by an hour and a half, adding that a long-term lack of sleep contributed to heart disease and cancer.
Concern has been rising about the disruptive effects of back-lit screens but until now scientists had not tested their effects on sleep. Researchers at Harvard University and Brigham and Women’s Hospital in Boston asked 12 people to read an e-book on an iPad before bed some nights, and a printed book on other days.
When reading on a screen, the volunteers took ten minutes longer to fall asleep, and had ten minutes’ less rapid-eye movement (REM) sleep and lower levels of melatonin in the evening, equivalent to a delay of an hour and half in their daily rhythms, researchers report in the Proceedings of the National Academy of Sciences. “They felt more alert earlier in the day if they were reading a printed book than in the condition when they were reading an e-reader,” said Anne-Marie Chang, who led the study. “It was about midday before they caught up.”
People in the study were forced to stop reading at 10pm, but Dr Chang said in the real world they wold probably sleep for less time as well, putting themselves at risk of illness in the long term. “The evidence is that deficiency in the amount of sleep or quality of sleep may have a serious impact on their health in terms of cardiovascular disease, type 2 diabetes and cancer,” she said. “I think it is fair to say it could have serious consequences for your health and wellbeing.
“When you hold these devices up close to your face you’re looking directly in the light source, whereas external light is pointing elsewhere and reflected, and that’s a lot less.
“I really think that this is an important area for further study. If you count up the amount of time people spend on light-emitting devices, checking email, social media, watching TV, that will quickly add up . . . The very best way would be to avoid light-emitting devices in the hours before bedtime.”
Professor Russell Foster, the head of the Sleep and Circadian Neuroscience Institute at the University of Oxford, said: “This is the best study we have looking at e-books, iPads and their impact on sleep and alertness. It would have been interesting to compare reading for shorter periods of time [but] what it does is underline the importance of taking sleep seriously. The real issue with these devices is increasing your level of light, which will increase your level of alertness, and that will delay the onset of sleep.”
He recommends avoiding bright lights at bedtime and not drinking caffeinated drinks after lunch.
Source : http://www.thetimes.co.uk/tto/health/news/article4305123.ece