Nearly one in four teenagers are ‘ almost constantly ’ online as their lives are swallowed up ever more by their mobile phones , a study has revealed . Some 24 per cent of 13 to 17-year-olds admitted they were continuously checking their devices , including when they were at school . Nine in teenagers also confessed to going online every day as they were unable to resist the lure of Facebook and Instagram . In danger ? The study also looked at social media and found that middle class teenagers were more likely to use Snapchat , the controversial message service where messages disappears seconds after they are sent . Parents now find it increasingly difficult to monitor their children 's online behaviour as more than 70 per cent of teens use now more than one social network . The study was carried out on American teenagers but the findings would likely be worse in the UK as more British teenagers own smartphones than their US counterparts . The Pew Research Centre asked 1,060 children aged between 13 and 17 about their phone habits . The report found that what Pew described as a ‘ frenzy of access ’ was facilitated by mobile phones - particularly smartphones . Of the 92 per cent of teens who went online every day , more than half said that meant using their phones several times a day . Some 12 per cent admitted to using a gadget once a day , six per cent said they went online just once a week and a mere two per cent said it was less than that . Addicted : Overall Facebook remains the most used social media site among teens with 71 per cent using it . In the largest ever systematic study of emails - examining more than 16 billion messages - researchers have found that most people send replies containing just five words . The study , which was conducted by researchers at Yahoo Labs and the University of Southern California , also found that our email habits also follow remarkable patterns . Replies become faster as the conversation progresses , but the researchers found they could tell when a email thread was about to end as the last reply was much slower than the previous replies . 'The long delay in a reply could be considered as a signal for the end of the conversation , ' said the researchers , led by Farshad Kooti , a computer scientist at the University of Southern California . The study examined the emails sent by two million Yahoo users over a period of several months . They found that on average younger people tend to spend less time composing an email - with a reply time of around 13 minutes on average for teenagers . Young adults take 16 minutes , while those aged 36 to 50 years old spend around 24 minutes before sending their reply . Phone ownership was almost ubiquitous among young people , meaning they grow up used to being able to access anything any time they want . The Pew study found that nearly three-quarters of teens have access to a smartphone . Some 30 per cent have a basic phone and just 12 per cent of 13 to 17-year-olds have no phone of any kind . The study also looked at social media and found that middle class teenagers were more likely to use Snapchat , the controversial message service where the text and images disappears seconds after they are sent . The service has been blamed for a rise in ‘ sexting ’ , where young people send explicit pictures to each other . Overall Facebook remains the most used social media site among teens with 71 per cent using it . Amanda Lenhart , the lead author and associate director of research at the Pew Research Centre , said : ‘ There ’ s been a huge diversification of social media . ‘ If you are wondering where your child is , you probably need to cast a wide net , because there is a variety of places where your teen could be spending his or her social media time ’ Previous studies have starkly illustrated the extent to which young people are addicted to their mobiles . Smartphone users check their devices an average of 150 times a day as they can not bear to be apart from them , one research paper showed . The study showed that we are so addicted to their mobiles that we can not go 10 minutes without fiddling around with them .
9 in 10 teens go online every day , unable to resist the lure of the Pew Research Centre . Parents also face a nightmare monitoring children as 71 % of teens use more than one social network , Facebook found . Nearly three-quarters of teens have or have access to a smartphone .