Stockholm, March 8 A clear majority of young Swedes used digital devices in bed before going to sleep, with one in three having trouble getting properly rested, a media report said. A third of respondents aged 15 to 29 said they had trouble sleeping, a poll cited by public broadcaster Swedish Television found, while 82 percent of that group said they use digital devices in bed before going to sleep. "The very use of social media makes one active. In order to sleep, the brain needs to calm down," Torbjorn Akerstedt, a professor at Karolinska Institutet in Stockholm, told the channel. The blue light emitted by screens tricks the body into thinking it is day time, while at the same time suppressing the production of melatonin, a hormone that helps people sleep, the channel reported. One quarter of the young people polled said they would like to be able to switch off their access to social media during particular hours, Xinhua reported. Nearly half the young respondents said they are sleeping worse today than five years ago, while 31 percent said they believed social media is disturbing their sleep. Nearly two thirds said they had trouble concentrating on daily tasks due to a lack of sleep.