This postal questionnaire study investigated the use of media in the bedroom and its relationships with sleep habits and symptoms of insomnia. The sample comprised 2500 individuals aged 16-40 years drawn randomly from the Norwegian national register. A total of 816 (34.0%) completed and returned the questionnaire. Respondents were asked how often they used computers, television sets, DVD players, game consoles and mobile telephones and listened to music/radio in their bedrooms. They also reported sleep habits on weekdays and at weekends/days off and symptoms of insomnia. After controlling for gender, age, anxiety and depression, the respondents who used a computer in the bedroom 'often' compared to 'rarely' rose later on weekdays and at weekends/days off, turned off the lights to go to sleep later at weekends/days off, slept more hours at weekends/days off and had a greater discrepancy between turning off the lights to go to sleep on weekdays and at weekends/days off. Respondents who used a mobile telephone in their bedrooms at night 'often' compared to 'rarely' turned off the lights to go to sleep later on weekdays and at weekends/days off, and rose later at weekends/days off. No such differences were found with the use of the other media. There were also no significant differences in symptoms of insomnia. This study indicates that the use of computers and mobile telephones in the bedroom are related to poor sleep habits, but that media use in the bedroom seems to be unrelated to symptoms of insomnia.