Of the 500 parents of pupils aged five to 16 polled, a fifth said their child had slept badly at least once during the previous month. For younger children the main reason was nightmares, followed by worrying about Sats and bullying by teachers or classmates.

Three-quarters of parents with a child due to take key stage 2 tests next week said they had helped them to revise. One in 10 parents of children who have taken the tests said they had lost sleep over them in previous years.

The survey, by FDS International, found that children with a TV in their bedroom slept for half an hour less on average than children without.

Almost 70 per cent, including 40 per cent of under-eights, have their own set. This was the case in half of the homes of professional parents and eight out of 10 of the poorest homes.

Most parents are not worried about what their children watch, but a quarter said they were concerned about some programmes shown before bedtime. Of those, about half named the BBC soap EastEnders as unsuitable.

Nine per cent of state schools and 18 per cent of independent schools already recommend bedtimes or minimum hours’ sleep for pupils, and the poll showed that 40 per cent of parents wanted their school to do this.

Chris Davis, head of Queniborough primary near Leicester and chairman of the National Primary Headteachers’ Association, said: “Losing sleep over tests is a minor part of it. We have had children being sick during the weekend before the tests.”

News 4-5, Leader 22