Children should not watch TV, tablet or mobile phone screens before bedtime. Researchers found "screen time" before sleeping is bad for children's health. The researchers looked at studies on how bad screen time is for children. They said that 90 per cent of the studies found that screen time delays bedtime. It also leads to less sleep, and poorer sleep quality. Screens are small, so children look at them in bed. Most children have a screen in their bedroom.

Children need more sleep than adults. Pre-school children need up to 13 hours, pre-teens up to 12 hours, and teenagers up to ten hours a night. There are three reasons why screens affect children's sleep. First, the light from screens upsets a child's body clock. It makes children think it is daytime. Second, videos excite children and keep their brain active, so they take longer to sleep. Finally, children are not exercising, so they are not tired.