ALMOST every parent knows the stress of having to "drag" our teenage children out of bed in the morning. Shouts and sulks are common fare.
Teenagers seldom emerge from sleep without cajoling, and we know they are often grumpy and sullen, only to improve in the course of the day. We sometimes forget that we were like that too, when we were teens.
Night after night we promised ourselves that we would retire to bed early, only to be distracted by television. Now we blame computer games for reinforcing these bad habits.
In recent years, neuroscientists' knowledge of the teenage brain has increased dramatically, and this has helped us understand why and how young people behave in the way that they do – sometimes thoughtlessly, taking risks and paying little heed to how their behaviour might affect them in the long term.
We know that the parts of the teenage brain concerned with risk taking, forward planning, and decision making are underdeveloped, and only reach full maturity in the early 20s.
Neuroscience also teaches us that there is a difference between the sexes, with girls achieving maturation a few years earlier than boys.
It is hardly surprising that sleep patterns, driven as they are by the brain, also vary over the lifespan. So teenagers, as in other aspects of their development, have a difficult time, even in slumber.
As research shows, it is not just laziness or faulty habits that determine this, although they may contribute, but the body's internal clock. Sleep research focused on teens is less well developed than for other age groups but it is progressing.
What is known is that young people are programmed to go to sleep at around midnight. It is also accepted that there is a myth that they need much less sleep than children, when in fact they need about 9 hours or more each night.
According to US researchers, 25pc of teenagers get less than six hours of sleep each night. They are not properly awake until midmorning, and learning is optimal in the afternoon. In general the circadian (daily) rhythm is shifted forward by about two hours in teenagers, in comparison to that of children, and it moves back again at about the age of 21.
Unfortunately the secondary school timetable, as it currently operates, is mismatched to the young person's internally determined body clock, and instead is synchronised to adult body rhythms. This results in "sleep debt" and this has been shown to have inevitable consequences for learning.
This information from research suggests that ideally, at least from the pupils' perspective, school should start in late morning and end in late afternoon. For the first time, one school in Britain reports going some way towards acting on this knowledge. University College London Academy in Central London opened in September 2012. Classes begin at 10am and finish at 5.30pm.
Reports so far are promising. Throughout the world, schools are slowly adopting the practice of later opening and delayed closing. In North Carolina, one such project found that starting school one hour later boosted reading and maths scores in 11-14 year olds. A study among 19-year-old US air force cadets found that they achieved better exam results when their classes shifted from 7 to 9am.
Campaigners for change report that they are often disbelieved, or are viewed as colluding with teenage laziness. One of the problems, which even sleep researchers acknowledge, is that even with changed school times, attention to sleep hygiene is also required. This means going to bed at the same time every night, avoiding overstimulation beforehand, and so eliminating stimulating drinks such as coffee or coke in the late evenings.
It also requires a reduction in the amount of time spent playing computer games or watching television, and keeping the bedroom cool – demands that many teenagers would find impossible to meet.
It is unlikely that teachers or parents will be willing or, in many cases, able to make the changes in their time schedule to facilitate these new school arrangements. Few have the luxury of flexible work arrangements that allow them to begin at 10am or later.
Changing the time patterns that have been set for decades, no matter how desirable for young people's academic development, may be something that is only for the affluent and self-employed.