Teenagers in California are about to get some much-needed extra sleep. A new law passed early this month will push start times later for most schools; high schools will start no earlier than 08:30 and middle schools 08:00.
The move is aimed at improving teenagers’ school performance by ensuring they are adequately rested. There’s a sizeable body of research behind it; although teenagers may have a bad reputation for staying up late, sleeping in and sleeping longer than any other demographic, the science shows that it's not their fault.
Biologically, teenagers have a different circadian rhythm to people of other ages. Their internal body clock, which tells them when and how long to sleep, doesn't line up well with the norms of the social clock. Forcing teenagers out of bed early in the morning to go to school can affect their physical and mental health, attention span and ability to learn.
And though teenagers may be a special case, they are hardly the only ones suffering. Waking and sleeping in a pattern that's out of synch with your body clock results in a phenomenon known as 'social jet lag' – something that affects swathes of society.