Do teenagers need longer in bed?

The act of sleeping is universal across all species, but there are big differencesbetween them. Giraffes sleep for 2 hours, chipmunks snooze for 15 hours and us humans, well we sit in the middle of the spectrum at 8 hours. But when and how long should we sleep for? We're told to make sure we get a good 8 hours kip every night to stay healthy, but research suggests that when and how long we sleep changes with age. So should we be adapting our lifestyle to suit our sleep needs? Colin Espie is a professor of sleep medicine at the University of Oxford and spearheading a ground-breaking study that will mean tens of thousands of teenagers will start school an hour or two later to see if more time in bed and a later start-time for classes can improve exam results. Kat Arney spoke to him about about the experiment and began by asking how sleep-needs change throughout our lives...

Colin - I think a way of thinking about sleep across the lifetime is that, it's kind of titrated or adjusted to meet the developing needs of the individual. So, the newborn baby needs a.) a lot of sleep, and b.) a lot of particular types of sleep. For example, a lot of slow wave sleep for growth, a lot of REM sleep (rapid eye movement sleep), because of the coding of all the new learning that's happening. But of course, your learning continues throughout your life, but it doesn't accelerate the way it is from newborn, so you don't need so much sleep. We know that the time you go to school, you're no longer napping during the day - at least your primary school teacher wouldn't appreciate it - whereas your nursery teacher is okay with it. So, there's another change that sleep becomes consolidated into the night time period. Of course, then we have the teenagers who seem to be defying their parents, saying they are not sleepy, and then they're sleepy in the morning. We know that just as their other developmental changes, sleep is affected. Not just sleep but your circadian rhythm.

Kat - Of course, they have to get up and go to school. Tell me about the study that you're doing to maybe try and help them out of it.

Colin - We want to test the hypothesis that a later school start time will pay dividends to the learning of the young person as evidenced by better school leaving qualifications. Now, that is a big ambition. But there's good biological reasons that if teenagers are learning at a more optimal circadian time that they will do better. But that's just one arm of the study. We want to test that with another element, which is a sleep education programme. Often, sleep is missed off the agenda. We talk about nutritional needs, we talk about exercise needs at school but not much about sleep. So, we want to help and want the teachers develop a curriculum on sleep for skills. So these two elements, we will test separately and together in this trial and then the fourth arm of the study will just be as things are at the moment. And by having this design, we should be in the best position tease out what is most effective.

Kat - Do you have any idea of what kind of improvement you might be hoping for? Is this the difference between an A grade and a C grade?

Colin - That's a very good question and I wouldn't like anticipate exactly what the level of difference should be because some people will be markedly helped by this one but we would anticipate, in others, much less and then you end up with an average statistic. It's a bit akin to an intervention that you can use a public health level. So, what we're trying to do is, if you like, shift the whole population curve in terms of its performance. Within that shift, there'll be some people who have benefited more and other people, a bit less, but we don't think it will do harm to anyone. If you ask any teenager, I think they'd be enthusiastic with this study.