There was good news last week for people who struggle to get eight hours of sleep a night: they may not need so much shut-eye after all.

    Researchers from UCLA and elsewhere looked at sleep habits of remote hunter-gatherers in Tanzania, Namibia and Bolivia — groups with pre-industrial lifestyles whose sleep patterns are believed to reflect those of ancient humans. The researchers found that, on average, members of each group sleep a bit less than six and a half hours a night.

    The study, published in the academic journal Current Biology, indicates that “natural” sleep is less than eight hours a night and that modern society's numerous electronic distractions (分心) aren't necessarily to blame for people getting just six or seven hours of sleep.

    “The story that often gets out is that if you sleep for less than seven hours, you're going to die early,” he told me. “That's not true.”

    Yet Americans are addicted to getting more sleep — and on turning to medical shortcuts to help them.

    According to the Centers for Disease Control, as many as 70 million U.S. adults suffer from sleep disorders or sleeplessness. Only a third of Americans get the government's recommended seven to nine hours of sleep a night.

    About 9 million American adults use sleeping pills to help get a good night's rest, the CDC found. Siegel said the number of people relying on medicines “has gone up rather rapidly since then.”

    Industry consulting firm Global Data estimates that worldwide sales for sleeplessness medicines will run about $1.4 billion next year and reach $1.8 billion by 2023, recovering from lower sales in recent years because of cheaper generics(仿制药) hitting the market.

    Dr. Roy Artal, a sleep specialist in West Los Angeles, said it's understandable that busy people in today's go-go world would turn to medicines to speed up the sleep process. But all they're doing is building a reliance on powerful drugs for relatively little improvement.

    “There's no magic pill that makes us sleep when we want and wake up when we want,” Artal said. “The effects of sleeping pills tend to be modest.”

    He and other experts say the answer to sleeplessness isn't to be found in a pill bottle. It's in what's called “sleep hygiene (保健).”

Five ways to improve creativity

    Creativity is the ability to go beyond traditional rules, ideas or relationships and create something new through imagination or progressiveness. There are many ways to improve your creative mind.

    Exercise the mind. Exercising your mind is an ideal way to boost creativity. Like the body, the mind needs exercise to work the creative muscles and make them stronger. Exercise your brain by learning new subjects, getting into a debate about politics and talking to other creative and intelligent people.{#blank#}1{#/blank#}

    Be passionate. One aspect of creativity is passion.{#blank#}2{#/blank#} Find your internal motivation and follow your passion to improve your creativity.

    Change your routine.{#blank#}3{#/blank#}To boost your creativity, consider changing one to two elements of your daily routine. If you are working on a certain project, consider stopping one project to work on another project at regular intervals throughout the day or week.

    Read. While reading provides many intellectual benefits, reading is also beneficial for boosting creativity, exercising your brain and provide creative inspiration.{#blank#}4{#/blank#}Consider reading about subjects that were previously uninteresting to you. This change in the norm might spark your creative interest.

    {#blank#}5{#/blank#} Our packed schedules have no room for creative thinking. Take a certain amount of time every day to quiet, refresh and clear the mind while relaxing the body. This quiet time can consist of a yoga workout, meditation or simply sitting still in a dark and quiet room, in a peaceful garden or on a beautiful beach.

A. Schedule quiet time.

B. It can become weak due to stresses

C. Creativity is a natural quality

D. Often, creativity is blocked due to a too familiar routine

E. These activities will encourage a flow of creativity.

F. Read as much as possible about several different subjects.

G. Typically, students will do well in subjects they are interested in

    In the story of “The crow and the Pitcher” from Aesop's Fables, a thisty crow (乌鸦)drops stones into a narrow jar to raise the low level of water inside so he can take a drink.

    Now scientists have evidence to back up that story. Crows actually do understand how to make water displacement (移位) work to their advantage, experiments show. The results suggest that the birds are, at least in some aspects, as smart as first-graders.

    Researchers, led by Sarah Jelbert at the University of Auckland in New Zealand, presented six crows with tubes filled with water. Inside the tubes, a worm or piece of meat on a piece of wood was floating, just out of reach of the crow. In front of the tubes, the researchers arranged several rubber erasers that would sink, and some plastic objects that would float. The crows found out that they could drop the erasers into the tubes in order to raise the water level and get their snack.

    However, the birds handled awkwardly in experiments in which they could choose to drop objects in either a wide tube or a narrow one to get a snack, the researchers said. Dropping objects into narrow tube would lift the water level by a greater amount and put the treat within reach after just two drops; while it took around seven drops to raise the snack to the same level in the wide tube. The crows obviously didn't realize this, and most of them went for the wide tube first.

    Previous studies showed that chimps and human children can solve similar tasks. In a 2011 study, chimps and kids found out that they could put water into a tube to reach a peanut that was floating in a small amount of water at the bottom.

How to Prevent Dehydration

    When the weather's warm, you need to make sure you drink enough water. But did you know that you lose your sense of thirst as you get older? This means you5re more likely to become dehydrated, making you more prone to (有倾向) falls, heart disease, urinary-tract infections, kidney stones and confusion. A study from Loughborough University in the UK has shown that drivers who had only a little water an hour made twice as many mistakes as motorists who were properly hydrated. In fact, they made a similar number of errors to what you'd expect from someone over the drink-drive limit.

    So how do you know when you're dehydrated? Warning signs include:

    Feeling tired

    Dry mouth and dry skin

    Dark urine

    Reduced appetite (食欲)

    Reduced concentration

    Headache

    Constipation.

    But you might not notice any symptoms (症状)at all，so to make sure you stay hydrated:

    Keep a glass of water by your side when you're at home, and drink it regularly.

    Form a new drinking habit—for example, when watching TV, always reach for the water glass during an ad break.

    Take a small bottle of water with you when you go out.

    Always drink a large glass of water with a meal.

    Eat fruit and vegetables with high water content.

    Draw up a weekly water card—a bit like a coffee loyalty card—with a target of eight glasses of water a day. Mark it every time you have a glass of water. Award yourself a prize when ifs full at the end of the week.

    Drink water before, during and after you take any exercise.

I've spent over a year in India, and in those 365 plus days, I've learned a lot about getting around Indian cities. My biggest lessons have been learned through being cheated, particularly by taxi and rickshaw (人力车) drivers, but that doesn't mean those are bad ways to travel, as long as you know what you're doing. Below are the best ways to get around the city of Delhi, India, and tips for how to keep from being the victim of scams (欺骗).

Taking taxis is a great way to get around the city of Delhi and chances are, if you arrive in Delhi by plane, as soon as you make it through customs, you'll be swarmed by Indian taxi drivers. At the Delhi airport, be sure to arrange for a taxi to your hotel at one of the two Delhi Traffic Police Taxi Booths. One is inside the airport, and one is outside. The key is to make sure to go to a booth run by the police, rather than by independent taxi drivers.

Rickshaws are one of my favorite ways to get around Indian cities, in part because it's how the locals often travel. Auto­rickshaws are more common, but bicycle rickshaws are still used in Old Delhi. If you do have a chance to take a bicycle rickshaw, you should do it at least once for a unique experience that should only set you back about 15 rupees. Auto­rickshaw rates around Delhi range between 30 and 80 rupees, depending on distance.

If you really want to travel around Delhi like the locals, take a public bus. Indian buses become very crowded and most do not have air conditioning. They are, however, very cheap. A bus trip won't set you back any more than 15 rupees, as long as you stay within the city limits. Since Indian buses get so crowded, try to board the bus at the start of the route so you can get a seat.

The train is a great way to get around within the city of Delhi. Fares are reasonable, between six and 22 rupees. All departure announcements are in both Hindi and English, and tokens can be purchased for between 6 and 22 rupees.

Deforestation in tropical(热带的) regions of Asia, Africa and the Americas has reduced the cooling effects of trees. "The temperature change associated with deforestation over the 15-year study period is equal to a century of global warming, happening almost instantly, at these locations," says Luke Parsons at Duke University in North Carolina.

Now, by using data from population surveys and mapping tree cover loss over a 15-year period, Parsons and his colleagues have estimated the effect of deforestation on outdoor workers across 41 countries. He says climate change has already pushed tropical locations right to the edge of what would be considered safe for heavy outdoor labour and that deforestation causes those locations to be even more precarious.

Parsons and his colleagues used land surface temperature measurements from satellites, and collected humidity(湿度) data, to estimate how hot an average day felt to outdoor workers in regions which either lost or maintained tree cover between 2003 and 2018. "The study focuses on what you would think of as a 'feels-like' temperature. It takes into account how well you can cool yourself by sweating, which is affected by humidity, as well as the temperature," says Parsons.

The researchers then turned to population surveys to estimate the number of outdoor workers in these areas. This revealed that some 2.5 million outdoor workers in Asia lost at least half an hour of safe work per day, between 2003 and 2018, due to increased temperatures in deforested regions. Nearly 200,000 outdoor workers in the Americas and some 31,000 people in Africa lost this amount of safe work time each day. Regions that maintained forest cover generally stayed cool, and less work time was lost.

It is important to remember that, due to the scale(规模) of the study, the team didn't measure actual worker hours on the ground across the entire tropics, says Parsons. This means the assessment of lost worker hours is based on theoretical considerations rather than direct observations of behaviour.