Teens are dying for lack of sleep

Teenagers should not start school before 8.30am because tiredness is linked to car crashes, suicide, depression and poor performance, experts have said.

The US Academy of Sleep Medicine warned that early lessons caused sleep deprivation for pupils, which had a huge impact on their lives. They said later start times optimised daytime alertness, reduced tardiness and improved school attendance.

Teenagers aged between 13 and 18 are advised to sleep between eight and 10 hours but most report sleeping seven hours or less on school nights.

Experts warned that school times worked against adolescent circadian physiology, which could be nearly three hours behind that of an adult, leading to chronic sleep deprivation.

A lack of sleep could lead to poor school performance, obesity, heart problems, metabolic disorders, suicidal thoughts, risk-taking behaviours and athletic injuries. Dr Paul Kelley, a neuroscientist at The Open University in the UK, said: "I actually think teenagers shouldn't start school until 10am or later. Circadian rhythms shift dramatically during puberty and that impact continues right through university years."

In the US insufficient sleep is associated with an increased risk of motor vehicle accidents, which account for 73% of deaths from unintentional injury in teenagers. Previous research has found that crash rates decline by 16.5% when school start times are delayed by one hour.