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Snooze and you don't lose
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Snooze and you don’t lose Schools in the US and beyond are right to consider a later start time. Your teenager’s biology demands it, says Russell Foster A TENDENCY to sleep at a set time each day defines an individual’s “chronotype”. Although strongly influenced by genetics and light exposure, age-related body changes play a key role. Puberty heralds a notable shift as bedtimes and wake-up times get later. This trend continues until 19.5 years in women and nearly 21 in men, then gradually reverses. By 55 we wake at around the time we did as young children, approximately 2 hours earlier than as adolescents. So a 7 am alarm for a teenager feels like a 5 am start for a person in their 50s. The reasons are unclear but tally with the hormonal and neural changes of puberty and the drop in these hormones with age. This has consequences. A Canadian study compared cognitive performance midmorning and mid-afternoon in teenagers and adults. Test scores
in teenagers rose by 10 per cent from morning to afternoon; in adults they declined by 7 per cent. These findings highlight an important dilemma. Teachers in their 50s will generally be at their best in the morning, unlike their teenage students, and teachers set timetables. The tacit assumption for over a century has been that students are most alert in the morning and more demanding subjects should be taught then. This is wrong for most teenagers. An adolescent chronotype also leads to another issue: lack of sleep. Teenagers need about 9 hours for best academic performance. Many get far less. The circadian system is not totally to blame. More relaxed attitudes to bedtimes, ignorance about sleep and the near addictive use of social media make this worse. Insufficient sleep is about more than feeling tired at the wrong
An achievable dream We really could run the world purely on clean, renewable energy, says Mark Jacobson PEOPLE often ask me if I think there is any hope that the world can transition to clean, renewable energy fast enough to avoid the deadly and damaging impacts of a rapidly warming planet. I say yes. That’s despite a popular belief that we are doomed because a lot of politicians are wedded to fossil fuels. There are also those who 26 | NewScientist | 9 September 2017
energy journal Joule, our team at Stanford University and the University of California, Berkeley, set out road maps to achieve 100 per cent clean, renewable energy in 139 countries, responsible for more than 99 per cent of all emissions. These show how a transition of all forms of energy for all uses to electricity is possible, supplied by 80 per cent wind, water and solar power (WWS) by 2030 and 100 per cent by 2050. The study found not
question the practicalities: for example, how to keep a supply grid stable with 100 per cent, as opposed to 80 per cent, clean, renewable energy. Plenty of studies show it is possible. “Shifting all forms of energy Despite the naysaying, I remain optimistic that a complete for all uses to electricity is possible, supplied only by transition can happen globally. wind, water and solar” In the first issue of sustainable
only that it is possible, but also that this would bring big gains, including averting most of the millions of annual deaths attributed to air pollution. It would also stabilise energy prices and create in excess of 24 million more permanent, full-time jobs than are lost. Access to power for billions of people in energy poverty would improve, and demand would be reduced by about 43 per cent – due chiefly to the greater efficiency of electricity over combustion and the elimination of energy use for producing and moving fossil fuels. Importantly, moving to renewables would eliminate
For more opinion articles, visit newscientist.com/opinion
Russell Foster heads the Sleep and Circadian Neuroscience Institute at the University of Oxford, and is co-author of Circadian Rhythms – A Very Short Introduction (Open University Press)
nearly all emissions associated with global warming, helping us avoid reaching 1.5°C of warming this century, the Paris climate agreement’s most ambitious goal for avoiding climate disaster. I am confident that the transition is technically and economically possible, but it requires a massive increase (by a factor of between 10 to 100) in public and private action around the world. All of us can play a part in this. n Mark Jacobson is a professor of civil and environmental engineering at Stanford University and co-founded the Solutions Project, a clean energy campaign
INSIGHT Hurricane Harvey
SCOTT OLSON/GETTY IMAGES
time. Sleep promotes memory consolidation and problem solving, while shortened sleep can drive impulsivity, decreased empathy, self-harm, depression and increased use of stimulants. In the US, this has led to delayed school starts in several states. California is the latest to propose this. The logic has been reinforced by research estimating it could add $83 billion to the US economy over 10 years if done nationally, thanks to better academic performance and fewer car accidents. The proposal in the US, where 7 am starts are not unusual, is to begin at 8.30 am or later. In the UK most teens start around 9 am. Would 10 am be even better? Maybe, but big studies comparing 9 am and 10 am starts are needed. In addition, sleep education must be part of the solution. Teens have a shifted chronotype, but it can be exaggerated a lot by distractions such as social media. Teaching adolescents about the importance of sleep, as we do about smoking, alcohol and sex, will at least allow them to make more informed choices. n
–Where next?–
The cities in the firing line for future floods Michael Le Page
extraordinary amounts of moisture into the air over Texas. Sea levels have risen 0.2 metres over the past century due to global warming. This also compounded the situation, slowing the drainage of flood waters and making the storm surge higher. Finally, Harvey stalled for a long time after coming ashore, so huge amounts of rain fell in one area. This too might be linked to climate change. A growing number of studies suggest this makes weather systems more likely to get “stuck”. All these factors will conspire to increase the number and severity of
HURRICANE Harvey may have been unprecedented, but it wasn’t unexpected. Houston frequently experiences flooding and experts have repeatedly warned that worse could be to come as the world gets warmer. And yet Houston was shockingly unprepared, not least because its flood control directors think talk of climate change is a plot to prevent development, and its planning system fails to prevent building in the most at-risk areas. It is only a matter of time before more “unprecedented” flooding hits “Rich cities tend to have the US. Next in line could be other better flood protection, major cities such as Miami, New York and Boston. Yet relatively little is being but many wealthy US cities have low protection levels” done. In fact, just days before Harvey struck, Donald Trump rescinded rules that mean federal infrastructure extreme flooding events as global projects must take into account flood surface temperatures soar past 2°C risks related to climate change. above pre-industrial levels in the next Global warming may not have few decades. caused Hurricane Harvey to form, but So who else is in the firing line? In terms of the number of people at it made the storm worse. Abnormally risk, populous countries like India, warm waters in the Gulf of Mexico Bangladesh and China naturally come fuelled the hurricane’s rapid top. Millions in these countries are intensification, enabling it to pump
already affected by river flooding every year. Indeed, this year, abnormally heavy monsoon rains have caused severe flooding across southeast Asia, killing at least 1200 people. However, America features prominently in a list of the coastal cities facing the biggest financial losses from flooding by 2050, according to a 2013 study. The top five are Guangzhou, Miami, New York, New Orleans and Mumbai. In general, rich cities such as Amsterdam have much better flood protection than poorer cities in developing countries. But many wealthy American cities have low protection levels. It is clear the US needs to do more. Part of the answer is to stop building homes in harm’s way. This is not just a problem in Houston: since the 1960s, the US has provided cheap, subsidised flood insurance that has encouraged development in high-risk areas. This scheme’s $24 billion debt is set to soar thanks to Harvey. Big infrastructure projects have a part to play, too. Massive barrier schemes similar to the one protecting London have long been considered for protecting places such as New York City, but have yet to get the go-ahead. But it is simply not feasible to protect many areas, such as the vast swathes of Florida set to disappear under the waves over the next century. Abandoning those areas will be the only solution. n 9 September 2017 | NewScientist | 27
Snooze and you don’t lose Schools in the US and beyond are right to consider a later start time. Your teenager’s biology demands it, says Russell Foster A TENDENCY to sleep at a set time each day defines an individual’s “chronotype”. Although strongly influenced by genetics and light exposure, age-related body changes play a key role. Puberty heralds a notable shift as bedtimes and wake-up times get later. This trend continues until 19.5 years in women and nearly 21 in men, then gradually reverses. By 55 we wake at around the time we did as young children, approximately 2 hours earlier than as adolescents. So a 7 am alarm for a teenager feels like a 5 am start for a person in their 50s. The reasons are unclear but tally with the hormonal and neural changes of puberty and the drop in these hormones with age. This has consequences. A Canadian study compared cognitive performance midmorning and mid-afternoon in teenagers and adults. Test scores
in teenagers rose by 10 per cent from morning to afternoon; in adults they declined by 7 per cent. These findings highlight an important dilemma. Teachers in their 50s will generally be at their best in the morning, unlike their teenage students, and teachers set timetables. The tacit assumption for over a century has been that students are most alert in the morning and more demanding subjects should be taught then. This is wrong for most teenagers. An adolescent chronotype also leads to another issue: lack of sleep. Teenagers need about 9 hours for best academic performance. Many get far less. The circadian system is not totally to blame. More relaxed attitudes to bedtimes, ignorance about sleep and the near addictive use of social media make this worse. Insufficient sleep is about more than feeling tired at the wrong
An achievable dream We really could run the world purely on clean, renewable energy, says Mark Jacobson PEOPLE often ask me if I think there is any hope that the world can transition to clean, renewable energy fast enough to avoid the deadly and damaging impacts of a rapidly warming planet. I say yes. That’s despite a popular belief that we are doomed because a lot of politicians are wedded to fossil fuels. There are also those who 26 | NewScientist | 9 September 2017
energy journal Joule, our team at Stanford University and the University of California, Berkeley, set out road maps to achieve 100 per cent clean, renewable energy in 139 countries, responsible for more than 99 per cent of all emissions. These show how a transition of all forms of energy for all uses to electricity is possible, supplied by 80 per cent wind, water and solar power (WWS) by 2030 and 100 per cent by 2050. The study found not
question the practicalities: for example, how to keep a supply grid stable with 100 per cent, as opposed to 80 per cent, clean, renewable energy. Plenty of studies show it is possible. “Shifting all forms of energy Despite the naysaying, I remain optimistic that a complete for all uses to electricity is possible, supplied only by transition can happen globally. wind, water and solar” In the first issue of sustainable
only that it is possible, but also that this would bring big gains, including averting most of the millions of annual deaths attributed to air pollution. It would also stabilise energy prices and create in excess of 24 million more permanent, full-time jobs than are lost. Access to power for billions of people in energy poverty would improve, and demand would be reduced by about 43 per cent – due chiefly to the greater efficiency of electricity over combustion and the elimination of energy use for producing and moving fossil fuels. Importantly, moving to renewables would eliminate
For more opinion articles, visit newscientist.com/opinion
Russell Foster heads the Sleep and Circadian Neuroscience Institute at the University of Oxford, and is co-author of Circadian Rhythms – A Very Short Introduction (Open University Press)
nearly all emissions associated with global warming, helping us avoid reaching 1.5°C of warming this century, the Paris climate agreement’s most ambitious goal for avoiding climate disaster. I am confident that the transition is technically and economically possible, but it requires a massive increase (by a factor of between 10 to 100) in public and private action around the world. All of us can play a part in this. n Mark Jacobson is a professor of civil and environmental engineering at Stanford University and co-founded the Solutions Project, a clean energy campaign
INSIGHT Hurricane Harvey
SCOTT OLSON/GETTY IMAGES
time. Sleep promotes memory consolidation and problem solving, while shortened sleep can drive impulsivity, decreased empathy, self-harm, depression and increased use of stimulants. In the US, this has led to delayed school starts in several states. California is the latest to propose this. The logic has been reinforced by research estimating it could add $83 billion to the US economy over 10 years if done nationally, thanks to better academic performance and fewer car accidents. The proposal in the US, where 7 am starts are not unusual, is to begin at 8.30 am or later. In the UK most teens start around 9 am. Would 10 am be even better? Maybe, but big studies comparing 9 am and 10 am starts are needed. In addition, sleep education must be part of the solution. Teens have a shifted chronotype, but it can be exaggerated a lot by distractions such as social media. Teaching adolescents about the importance of sleep, as we do about smoking, alcohol and sex, will at least allow them to make more informed choices. n
–Where next?–
The cities in the firing line for future floods Michael Le Page
extraordinary amounts of moisture into the air over Texas. Sea levels have risen 0.2 metres over the past century due to global warming. This also compounded the situation, slowing the drainage of flood waters and making the storm surge higher. Finally, Harvey stalled for a long time after coming ashore, so huge amounts of rain fell in one area. This too might be linked to climate change. A growing number of studies suggest this makes weather systems more likely to get “stuck”. All these factors will conspire to increase the number and severity of
HURRICANE Harvey may have been unprecedented, but it wasn’t unexpected. Houston frequently experiences flooding and experts have repeatedly warned that worse could be to come as the world gets warmer. And yet Houston was shockingly unprepared, not least because its flood control directors think talk of climate change is a plot to prevent development, and its planning system fails to prevent building in the most at-risk areas. It is only a matter of time before more “unprecedented” flooding hits “Rich cities tend to have the US. Next in line could be other better flood protection, major cities such as Miami, New York and Boston. Yet relatively little is being but many wealthy US cities have low protection levels” done. In fact, just days before Harvey struck, Donald Trump rescinded rules that mean federal infrastructure extreme flooding events as global projects must take into account flood surface temperatures soar past 2°C risks related to climate change. above pre-industrial levels in the next Global warming may not have few decades. caused Hurricane Harvey to form, but So who else is in the firing line? In terms of the number of people at it made the storm worse. Abnormally risk, populous countries like India, warm waters in the Gulf of Mexico Bangladesh and China naturally come fuelled the hurricane’s rapid top. Millions in these countries are intensification, enabling it to pump
already affected by river flooding every year. Indeed, this year, abnormally heavy monsoon rains have caused severe flooding across southeast Asia, killing at least 1200 people. However, America features prominently in a list of the coastal cities facing the biggest financial losses from flooding by 2050, according to a 2013 study. The top five are Guangzhou, Miami, New York, New Orleans and Mumbai. In general, rich cities such as Amsterdam have much better flood protection than poorer cities in developing countries. But many wealthy American cities have low protection levels. It is clear the US needs to do more. Part of the answer is to stop building homes in harm’s way. This is not just a problem in Houston: since the 1960s, the US has provided cheap, subsidised flood insurance that has encouraged development in high-risk areas. This scheme’s $24 billion debt is set to soar thanks to Harvey. Big infrastructure projects have a part to play, too. Massive barrier schemes similar to the one protecting London have long been considered for protecting places such as New York City, but have yet to get the go-ahead. But it is simply not feasible to protect many areas, such as the vast swathes of Florida set to disappear under the waves over the next century. Abandoning those areas will be the only solution. n 9 September 2017 | NewScientist | 27