Teenagers. Why they are as they are.

Teenagers don’t tend to get a good press – whether its sulks, moodiness, excessive risk-taking, bad decision-making or sleeping late.

‘What’s happened to my sweet child?!’ parents ask.

But Professor Blakemore, a professor in cognitive neuroscience at University College, London, doesn’t think it’s their fault.

The changes in the brain are enormous, she says, with substantial rises in white matter and a 17% fall in grey matter, which affects decision making, planning and self-awareness.

Many parents know teenagers will sleep late if they can, but ‘it is not because they are lazy – it is because they go through a period of biological change where melatonin, which is the hormone humans produce in the evenings and makes us feel sleepy, is produced a couple of hours later than it is in childhood or adulthood.’

They are forced to go to school when their brain says they should still be sleeping. This is then exacerbated at weekends when teenagers try to catch up by sleeping until lunchtime – what Blakemore calls ‘social jetlag’.

‘They are constantly shifting their body clock from one time zone to another, which must be very disorientating.’

She also believes it is wrong to have such stressful GCSE exams at 16, when the teenage brain is going through such a big change.

‘This country is the only country in the world – apart from countries that follow our education system, like Commonwealth countries – that have big national public exams at 16. Given our children have to stay in some form of education until 18, we don’t need those exams. Why do we still have GCSEs?’

‘It doesn’t make any sense to me to impose this enormous stress, when we are so focused on grades, just at that precise moment in time.’

Blakemore says it matters because the teenage years are the time when people are more susceptible to mental illness – whether anxiety, depression, self-harm or addictions.

Not enough resources are being channelled to the issue, she says. ‘This is a hugely neglected area in terms of the amount of resource given to mental illness in young people. The government is paying lip service to it but we really need to see actual change rather than just words.’

Blakemore, the mother of a 10-year-old and a 13-year-old, says she is not the best person to give parenting advice, other than that she finds teenagers and adults feel empowered when they find out the facts about how much the brain changes during this time.

There might be a good reason why they’re still in bed at midday…