Electronic media are widespread and research has revealed connections between media use and sleep loss. In this study we aimed to elucidate how many media users get insufficient sleep and whether lengthy media use before sleep curtails sleep. Registered monitor members were surveyed twice on the Internet. The prevalence of self-perceived insufficient sleep ascribed by respondents to using electronic media before sleep was 48.0% (first survey) and 45.0% (second survey). Younger respondents more frequently ascribed using media before sleep as a factor in their perceived insufficient sleep than older respondents. After excluding respondents who ascribed their perceived insufficient sleep to factors other than the electronic media, the sleep duration before a workday was 6.38 ± 1.04 h for light media users (<2.5 h) before sleep, 6.20 ± 1.10 h for intermediate users (≥2.5 and <3.5 h) and 6.22 ± 1.09 h for heavy users (≥3.5 h). A Scheffe analysis revealed a significant difference between the light users and medium users (P = 0.02), and between light users and heavy users (P = 0.03). Only 29.0% of light users perceived they had insufficient sleep compared to 53.5% of heavy users. Users who perceived they had insufficient sleep reported a greater disparity in their sleep duration before workdays compared with that before non-workdays (P < 0.001) and a greater disparity between their perceived sufficient sleep hours and their actual sleep time before workdays (P < 0.001). There was a significant difference in disparity between perceived sufficient sleep and actual sleep time before workdays among media use groups (P = 0.002). Because half the respondents ascribed insufficient sleep to using electronic media, attention should be given to media use before sleep as a cause of perceived insufficient sleep.