The science behind adolescent sleep

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Why is it that young children have a tendency to wake up very early but, as teenagers, are reluctant to get out of bed until noon?

It turns out that it is biology, not just teenagers being lazy, as sleep researcher Wendy Troxel revealed in her recent TED Talk on “Why school should start later for teens“. During their adolescent years, teenagers experience a delay in their biological clock, meaning their bodies want to stay up late and sleep in. This is due to the release of a hormone called melatonin, which makes the body feel sleepy. In adults and younger children, melatonin is released at around 21:00, whereas in teenagers it is only released at about 23:00. This means that teenagers only feel an urge to go to sleep two hours after adults and younger children. Therefore, waking a teenager up between 06:00 and 07:00 (typical for most during term time) is the biological equivalent of waking an adult up at 04:00 to 05:00, which I am sure would leave them tired and lacking enthusiasm throughout the day. This is how teenagers feel every day during school time. Many stereotypical teenage characteristics such as depression and irritability could be products of chronic sleep deprivation due to a later release of melatonin and having to wake up early for school. School start times deprive students of two to three hours worth of the most valuable sleep, associated with memory consolidation, learning and processing emotions. A recent study revealed that only one in 10 teenage students gets the recommended eight to 10 hours of sleep per night. This isn’t just a problem – it’s an epidemic.

The consequences of this epidemic are vast. Firstly, sleep for teenagers helps to develop parts of the brain responsible for problem-solving, reasoning and judgement. These are all characteristics that help to reign in those distinctively risky teenage characteristics that so many parents are afraid of. At school, the effects of sleep loss are profound; concentration is significantly affected and it has been proven that sleep loss causes behaviours often associated with ADHD, which can cause lots of problems in the classroom. But the consequences go well beyond this. Chronic sleep deprivation has been proven to contribute to mental health problems, substance abuse, depression and anxiety. A study in Los Angeles Unified School District showed that teens with sleep problems were 55% more likely to have used alcohol in the past month than those with healthy sleep patterns. Another study of over 30,000 secondary school students showed that each hour of sleep lost contributed to a 38% increase in feeling sad or hopeless. Teenagers who are deprived of sleep are also at higher risk of many physical health problems that already plague the country, such as obesity, heart disease and diabetes. The consequences can put the general public in danger, as many 17-year-olds are on the road as recently-qualified drivers. Studies have shown that drivers getting five hours of sleep or less is the equivalent of driving with a blood alcohol content above the legal limit.

To solve this problem in America, where nearly half of schools start before 8:00, some schools have shifted their school start times back. School absences dropped by 25% in one such district and, unsurprisingly, academic achievement improved due to better concentration in class, with test results rising by 2-3%. This is the equivalent of replacing an average teacher with an outstanding one. Communities are now safer: in one school district, there was a 70% car crash reduction after they shifted their school start times back.

In the UK, Dr Paul Kelley of Oxford University has said that there is need for a huge change within society so that pupils and staff don’t have to start working, be it at school or in their job, until 10:00 for the best results. Dr Kelley was previously a head teacher at Monkseaton Middle School, where he changed the start of the school day from 8:30 to 10:00 and, coincidentally, the number of top grades amongst pupils rose by 19%. Oxford University is currently conducting a ground-breaking experiment to determine whether later school start times lead to better exam results. Tens of thousands of GCSE pupils from more than 100 schools are starting school at 10:00 for this experiment, with the results expected to be published in 2018.

Although all evidence points towards delaying school start times, I can’t see it happening any time soon, as you must then delay other start times to avoid logistical problems such as getting children to school. Other potential issues include the costs involved with changing after school clubs and scheduled bus times, but, in my opinion, the benefits would far outweigh the initial problems.