Unexpected connection between sleep and academic performance has been recently discovered.

Researchers have found that insufficient sleep and tiredness increase a person's risk of developing severe medical conditions, such as obesity （肥胖症），high blood sugar levels, and heart disease. Now, a new study has found that getting sufficient sleep is also the key to improving academic performance.

Jeffrey Gross, the university science professor who led the research, was not trying to find the relationship between sleep and grades when he handed out smartwatches to the 100 students in his chemistry class. Instead, the professor hoped the wrist-worn devices, which track a personas physical activity, would show a connection between exercise and academic achievements.

While Grosses data showed no relationship between these two factors, the study found something surprising. As the researchers were analyzing their data, they noticed that there was a linear （线性的）relationship between the average amount of sleep the students got and their results in the course's 11 quizzes, three midterm tests, and the final exam.

Even more interesting, it was not sufficient for students to just head to bed early the night before a test Instead, it's the sleep you get during the days when learning is happening that matters most.

When students went to bed each night was similarly important. Those who went to bed in the early hours of the morning performed poorly, even if the total sleep time was the same as a higher-performing student. "When you go to bed matters," Gross says. “If you go to bed at 10, or 12, or 1 at night, and sleep for seven hours, your performance is the same. But if you go to bed after 2, your performance starts to go down even if you get the same seven hours' sleep. So, quantity isn't everything."

Perhaps the most interesting was the huge impact that small differences in sleep patterns had on the students' grades. The overall course grades of students averaging six and a half hours of sleep each night were 25% lower than students who averaged just one hour more sleep. Similarly, students who varied their bedtime by even one hour each night had grades that dropped 45% below those with more regular bedtime.

Who knew getting straight AM just required some extra sleep?

Industry must speed up investment in new technologies that allow manufacture（大量制造）of materials using renewable electricity if net zero emission（排放）targets are to be met, research led by the University of Leeds warns.

Ensuring that no electricity is produced from fossil fuels by 2050 is vital for achieving net zero. However, its effect will be limited if industry cannot use this electricity. Steel manufacturing alone accounts for a tenth of all carbon dioxide（CO₂）emission in industrialised countries but latest estimates suggest new technologies to manufacture steel using electricity will not become fully operational until at least 2040.

The lead author of the study, Dr Alan Grainger, from the University of Leeds School of Geography, said, “Delays in replacing existing steel manufacturing capacity represent a crucial ‘lock in’ constraint（约束）on achieving net zero.” Humanity’s great dependence on steel, which accounts for 94% of all metal production, is a huge blockage that cannot be ignored. The UK Net Zero Strategy, published last week, recognizes this problem,but lacks detail on how to deal with it.

Governments should strengthen international carbon reporting standards for energy-intensive industries, the paper says, so that total levels of CO₂ production during the manufacture and lifetime of materials can be measured more obviously in assessing progress towards national net zero targets. The carbon price also needs to rise to make it economically viable（可行的）to introduce new manufacturing technologies with low CO₂ emission.

This is the greatest mystery of our adult life: How can we spend all day typing at a computer and go home feeling exhausted? How could merely activating the small muscles of our fingers leave us worn out at the end of the day? What causes mental fatigue (疲劳)?

“It is kind of a mystery, to be honest.” said Michael Inzlicht, a University of Toronto psychologist who studies self-control, motivation and fatigue. But scientists do have some clues. There is a hypothesis for why we get so tired from work when we’re not physically active. We get so tired because our motivation runs out. As we work on a task, we struggle to focus on it or eventually lose interest in it. We become less motivated to do the task. We become drawn to the things we want to do (scrolling social media or reading music blogs, for instance), rather than the things we have to do. And this tension possibly causes fatigue.

Researchers in the UK published new evidence that finds some indirect evidence for the motivational model. This study tracked 100 nurses in the UK over two 1-hour shifts.

Throughout the shifts, the nurses reported how fatigued they felt at regular intervals. They also wore devices that monitored and tracked the amount of physical activity they were engaged in. When the researchers investigated what could possibly explain the fatigue, they found some interesting patterns. Here's the result: there was no connection between the amount of physical work the nurses did and their feelings of fatigue. Instead, they found this small connection: the nurses who were least likely to feel fatigued from their work also felt the most in control of their work, and the most rewarded of it. These feelings may have boosted their motivation, which may have boosted their perception of having energy.

Inzlicht has also found evidence for the motivational model in his work. A few years ago. he and Carleton University psychologist Marina Milyavskaya monitored 159 students at McGill University in Canada for a week. “What was surprising to us was the biggest predictor of fatigue, not whether they had exerted self-control.” Inzlicht said. “Instead, the predictor was the number of temptations they felt.” “lf you’re typing at work, and if you’re anything like me, you got a few browsers open. These lead to temptations ,” he said. “Temptations make us less motivated to do our work, which, in turn, may make us tired.”

And there may be an evolutionary reason for why our brains would do this. “As an organism, we need to meet multiple goals to survive.” Inzlicht explains. We’re not solely focused on finding food or pursuing our passions in life. We need to do all these things to be a healthy, thriving species. “Because these multiple goals compete with one another (for our time), we need a mechanism in place that signals.” “Hey, stop doing that thing and do something else.” That mechanism, he suggests, could be fatigue.

In this light, boosting our motivation to stay on a task could lead us to feel less fatigued. One study found that just paying people some money when they’re exhausted can keep them on task. A similar thing is found in studies on physical endurance: People can be easily pushed to work beyond what they think is their physical limit.