They found that young people who often use social media are more likely to suffer from sleep disorders than those who use social media less. The researchers set out to examine the connection between social media use and sleep among young adults. Levenson, who led the study, noticed that these young adults are possibly the first "generation to grow up with social media." The researchers wanted to find out how often young people used social media sites like Facebook, Twitter, Histogram, etc. For the study, they gave questionnaires to nearly 1,800 adults, aged 19 to 32. On average, members of the study group used social media sites one hour a day. They also "visited various social media accounts 30 times per week." Thirty percent of the study's participants  reported having serious problems with sleeping. Those people who used social media a lot were three times more likely to have a sleep disorder. And those who spent the most time on social media were two times as likely to suffer from sleep disorders. Levenson said the number of times a person visits social media is a better predictor  of sleep problems than overall time spent on social media. If this is true, she adds, then practices that stop such behaviors may be most effective. What do you think "social media" in this passage refers to?
Newspapers. Radio and TV. Mobile phones. The Internet.