Of those who take a device to bed, the bulk are communicating with friends using social media or watching videos or films, the study of more than 2,200 students in nine schools across England and Scotland found.
The survey found that more than four out 10 girls felt they used the internet on a compulsive basis for socialising, the Guardian reported.
The poll was carried out on behalf of Tablets for Schools, a charity led by technology industry groups such as Carphone Warehouse and Dixons that campaigns for the increased use of iPad-like devices in education.
Despite its remit the group has now published an advice guide for pupils and schools about internet devices, advising they be switched off before bed and during study times, with set times allocated for online activity.
The study said fewer than a third of students who used web devices in bed said this was connected to homework, with those more likely to use a computer, phone or laptop in bed also more likely to report feeling addicted to the internet.
There were some gender distinctions, with 46 percent of girls saying they sometimes felt addicted to the internet, as against 36 percent of boys, but significantly more boys saying they felt a compulsion towards computer games.
The peak age for feelings of addiction was year 10, where pupils are aged 14 or 15, with 49 percent of those pupils reporting this. The greatest use of devices in bed comes a year later, with 77 percent of year-11 pupils. Aside from email the most commonly used sites at home were social networks like Facebook, Twitter and Snapchat.
While most students told researchers they were positive about the internet, a number expressed alarm at their apparent inability to disengage.