A multi-institutional team of researchers conducted the first study to evaluate how the duration of nightly sleep early in the semester affects first year college students' end-of-semester grade point average (GPA), Using Fitbit sleep trackers, they found that students on average sleep 6. 5 hours a night, but negative outcomes accumulate when students received less than six hours of sleep a night. The results are available in the Feb. 13 issue of the Proceedings of the National Academy of Sciences.

Sleep guidelines recommend teenagers get 8 to 10 hours of sleep every night. Many college students experience irregular and insufficient sleep.

David Creswell, the William S. Dietrich Ⅱ Professor in Psychology and Neuroscience at the Dietrich College of Humanities and Social Sciences, led a team of researchers to evaluate the relationship between sleep and GPA. "Animal studies have shown how critical sleep is for learning and memory," said Creswell. "Here we show how this work translates to humans. The less nightly sleep a first year college student gets at the beginning of the school term predicts lower GPA at the end of the term. Lack of sleep may be hurting students' ability to learn in their college classrooms. "

The study evaluated more than 600 first-year students across five studies at three universities. The students wore wrist Fitbit devices to monitor and record their sleep patterns. The researchers found that students in the study sleep on average 6. 5 hours a night. More surprisingly, the researchers found that students who receive less than six hours of sleep experienced a pronounced decline in academic performance. In addition, each hour of sleep lost corresponded to a 0. 07 decrease in end-of-term GPA.

"Once you start dipping(下降)below six hours, you are starting to accumulate massive sleep debt that can impair a student's health and study habits, compromising the whole system," said Creswell. "Most surprising to me was that no matter what we did to make the effect go away, it persisted."

This year saw the publication, in stages, of the sixth report by the UN's Intergovernmental Pancl on Clinate. Change (IPCC)--a report which was depressing reading for ruany climate scientists, and in some ways offered a ray of hope. 

Why depressing? Because the report confinned what scientists have been saying for years: that human activity, particularly in the forrn of cmissions of greenhouse gases, is responsible for the warniing in the past few centuries, and that unless such emissions are greatly reduced, we will soon bring about our entire ecosystem's destruction. 

The report concluided that 1. 5℃ of global warming over the next couple of hundred years is already "baked      in". This makes the goals outlined in the 2015 Paris Agreement--that nations agreed to keep wanning below 2°℃, and hopefiully below 1. 5°℃—much barder to meet. Worse still, the IPCC report was followed later in the year by the COP27 summit (峰会),described by Prof Dann Mitchell, as "a complete failure, other than some comnitinent to loss and damage. "

And the ray of hope? The IPCC's sixth report was broader in approach than previous studies--looking in-depth for the first tine at the role played in warming by short-ferm greenhouse gases such as methane(甲烷), for instance. 

"Reducing carbon emissions is always the best approach: stop the problem at its source," said Mitchell. "But we also need other approaches to help with this. Methane is important but it's so short-lived—that's why we haven't been so bothered when compared with CO. "

The IPCC working groups showed potential adaptation paths, and they are the other things we can do in terms of fighting cliate change and relieving its worst effects, rather than simply reducing carbon emissions. This would include taking measures such as switching to a more piant-based diet (to reduce methane emissions), controlling population growth, reducing finansiai meqvallty and developing means by which we might remove CO that's already in our atmosphere, rather than simply preventing it being released. 

Many small American towns are known for their beautiful scenery, but very few have something special to offer. The following are known for their unique styles.

Scottshoro, Alabama

This attractive town is known as "The Lost Luggage Capital of the World" thanks to the unclaimed luggage center, where lost items such as snow skis, instruments and engagement rings are for sale. In addition to the store, which has become one of Alabama's top tourist and shopping attractions, the city's parks and heritage centers are popular places to visit.

Hope, Kansas

Hope is a city in southern Dickinson County, Kansas, with a population of 317. It's the home of Klipsch Museum of Audio History, President William Jefferson Clinton's birthplace and several antique shops. Hope's motto, which is also the name of the town's song, is "There will always be 'Hope' in Kansas".

Branson, Missouri

Although its population is just over 10, 000, Branson hosts over 9 million visitors each year. When the best-selling novel, The Shepherd of the Hills, written by Harold Bell Wright, was released in 1907, readers rushed to the Ozark hills to experience its famous views. Now tourists also get to visit the World's Largest Toy Museum, the world's largest Titanic Museum Attraction and the record-breaking theme park, Silver Dollar City.

Leavenworth, Washington

Leavenworth is a European-inspired destination, offering a collection of outdoor activities all year long. It welcomes almost 2million tourists each year and is home to the Nutcracker（胡桃夹子）Museum, which has more than 7，000 nutcrackers from around the world. Many of its visitors travel to the village in December during its annual holiday festival to see it light up with more than one million Christmas lights.