Climbing trees and spending hours playing outside used to be part of every childhood . But today ’ s youngsters are more likely to be stuck indoors – and it may be harming their eyesight . And it is not just because of the time spent sitting in front of a screen . For a lack of natural daylight is thought to be driving up rates of short-sightedness among the young . Spending an extra 40 minutes a day in the sunshine has been shown to improve children ’ s sight dramatically . Scientists had though reading or looking at a screen could cause shortsightedness , but now think it could be down to a lack of natural light while taking part in these activities ( file image ) In China , where four teenagers in five are short-sighted , transparent classrooms are being tested in a bid to increase pupils ’ exposure to natural light . Chinese scientists have reported a 23 per cent reduction in myopia – short-sightedness – in children who spend an extra 40 minutes a day in the sunshine . Studies in Australia and by Ohio State University in the US produced similar results . Leading eye surgeon David Allamby warned that an increase in eyesight problems is likely in Britain if children do not regain a love of the great outdoors . Two in five adults in this country are short-sighted , but Mr Allamby said those rates are likely to increase . ‘ For 100 years we have researched into the effects of reading and prolonged study on making short-sightedness worse , ’ he said . ‘ It has become a common belief that spending too much time inside a book , or today on a screen , will make anyone ’ s eyesight worse . ‘ Recent research might have turned this on its head . That ’ s why today some Chinese schoolchildren are going to school inside a big glass box . There are several studies showing that lack of daylight might be the principal reason why children become more short-sighted , rather than prolonged reading . Study shows that 40 minutes of extra natural light per day , by playing outside or climbing trees , could help to reduce cases by 26 per cent ( file image ) 'What wasn ’ t factored into our decades of research was that reading and studying are done indoors , away from daylight . ‘ The link between studying and myopia might really be a red herring , where the close vision activity is just a proxy for lack of daylight. ’ Donald Mutti , who led the Ohio study , told the journal Nature : ‘ We thought it was an odd finding but it just kept coming up as we did the analyses. ’ Mr Allamby , who runs Focus Clinics in London , said : ‘ The incidence of short sight in the West is rising , now affecting around 40 per cent of the population . ‘ If we look at hunter-gatherer societies that live mainly outdoors , such as those studied in Gabon , we find that only 0.5 per cent of adults are afflicted by short sight . ‘ Chinese children are participating in research to determine if more exposure to daylight will protect them from their myopic genes . ‘ If [ it ] is shown to help it might mean we all got outdoors more often . It could be time to invest in conservatory companies . ’
Researchers had thought reading or looking at screens caused condition . But now believe it could be because both of these activities occur indoors . Forty minutes extra of natural light per day could cut cases by today . Chinese children now being sent to schools with translucent walls .