Schools cave in to sleepy teens

* Victorian schools introducing late starts
* 40 per cent of teenagers 'chronically sleep deprived'
* Teen body clocks demand 'stay up late, wake late'

Secondary school should start at 10am to tackle chronic sleep deprivation in teens, experts say.

Oxford University sleep expert Russell Foster says teenagers are biologically wired to stay up late and wake late, making a 9am start too early.

Local psychologists Michael Carr-Gregg and Andrew Fuller agree.

Mr Fuller's local study found 40 per cent of teenagers were chronically sleep deprived.

Much of this is blamed on slack parents, electronic devices, a 24/7 culture and early school starts.

"We live in a society that doesn't value sleep," Mr Fuller said.

Prof Foster says the way teenagers are wired contributes.

While the mechanisms aren't fully understood, teenagers' biological clocks seems to make them want to stay up and wake late.

"I think many of us would guess that the changing patterns of steroid hormones during the teenage years are the strongest candidates for the cause of this altered timing," he said.

"It does seem to be something hard-wired at this time of development."

Prof Foster said people often dismissed teenagers as lazy, but it might not be all their fault.

"The real problem is that not only is the body clock delayed so that alertness comes later in the morning, but the amount of sleep many teenagers get is considerably reduced," he said,

"They go to bed late but still have to get up early for school. So there are two problems - a delayed body clock and shortened sleep."

Two Victorian schools have put their starting times back and are happy with the results.

Berengarra School in Glen Waverley and the Victorian P-12 College of Koorie Education in Mildura both start late.

Berengarra operates from 9.45am-3pm with shortened breaks and the Mildura school from 10am-3.40pm.

Both principals say sleep was a factor, and the change has helped alertness.

Prof Foster said there were social and practical problems in changing school start times.

"But if you can shift activities to a couple of hours later in the day most students will benefit," he said.

Dr Carr-Gregg said performance and enjoyment would improve if school better fit teenagers' body rhythm.

"Eighty per cent of year 10 students are not getting enough sleep," he said.

"The single most important study tool going around is a good night's sleep."

A State Education Department spokesman said: "We have not been presented yet with an overwhelming argument that we should change the current situation."