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).”

    How the Grand Canyon (大峡谷) was created remains one of the geology's greatest mysteries. Some evidence suggests that the process was a gradual one in which the Colorado River (which runs through the canyon) slowly cut deeper and deeper into the ground over millions of years. But volcanic rock samples taken from the canyon now suggest that the canyon was down-cut instead.

    Down-cutting is when a flood of water rushes over a landscape (地形) with enough force to cut deeply into the ground and leaves behind a canyon. Such a flood is usually released when a natural or man-made dam (堤坝) bursts.

    Robert Webb, a research geologist, says natural dams seem to have formed and broken across the Colorado River several times during the last million years. The dams were built when lava(熔岩) from the eruptions of nearby volcanoes flowed into the river. The lava hardened into hard rocks and blocked the river, causing it to back up and form a lake. Each time the lake grew so huge that it broke the rock dam, releasing a flash flood that furthered the down-cutting process and deepened the canyon.

    Down-cutting is not just an earthly event. Satellite photos sent back from Mars suggest that the process has happened there, too, say many other researchers.

    The photos, taken by the Mars Global Surveyor, indicate that an enormous lake existed on Mars 3.5 billion years ago. The lake spilled into a large nearby hole. One edge of the hole broke, releasing a flash flood that quickly carved out a grand canyon.

    The existence of down-cutting on Mars is just one more piece of evidence that the cold, dry planet was once warm and wet.

    When I was a boy there were no smart phones, computers were something you saw on STAR TREK, and our television only got one channel clearly. Still, I was never bored. The fields, hills, and woodlands around my home were the perfect playgrounds whose adventures were only limited by my imagination. I can remember once hiking to a nearby lake and slowly walking around it. At the backside of it I was amazed to find an old, one lane, dirt road that I had never seen before. I immediately set out to travel it. It was full of muddy tire tracks and deep woods bordered it on both sides, but exploring it still seemed like a fine adventure.

    I walked on and on for what seemed like hours. I am sure my guardian angel was whispering in my ear to turn around and head back home but I was stubborn and even a bit stupid, so I walked on. The dirt road gave way to a gravel one and then a paved one, yet there was still neither a car nor a house in sight. My legs were getting tired. I noticed that the sun was starting to go down and I grew scared. I didn't want to end up trapped on this road in the dark of night, but I was sure it would be dark before I could make my way back to the lake again.

    I continued to walk on with the something growing inside of me. My heart was pounding and my legs were aching. I was almost in tears when I turned one last curve and saw something in the distance. It was a house that I recognized. My heart leapt up! I jumped up and down and laughed out loud. I knew the way home! It was still over a mile away but my legs felt like feathers and I hurried back to my house in no time. I walked in with a big smile on my face just in time for dinner. Then I ended my adventure with a good night's sleep.

    I often thought of that experience recently. Actually, in our life, all roads, no matter how they twist and turn, can lead us home again. They can lead us to our homes here on Earth. They can lead us to our homes in our hearts. May you always walk your path with love. May you always help your fellow travelers along the way. And may your roads always lead you Home again.

    We are lucky to live in a world that is full of incredible technology. Our living rooms are packed with computers, LCD TVs, video game systems, and Blue-ray players that help us enjoy the latest entertainment. Although these items bring us joy and convenience, they also create a lot of junk. Each device needs its own plug and adaptor to keep its batteries recharged, and over time these wires get tangled (缠绕在一起的). Thankfully, something has come along to help rid our homes of this mess while still supplying these devices with the power they need. It's called wireless charging and this trend is just starting.

    Wireless charging has a lot of potential for smartphones and other electronic devices. Electronic devices can absorb the electricity once they're placed on a special charging mat. There are several advantages that wireless charging offers over traditional methods. For starters, cords (电线) have a tendency to wear out with use. Wireless charging users never have to worry about buying replacement cords. Wireless charging is also far more convenient for medical implants, as patients won't need to recharge their devices through the skin using cords. In turn, this cuts down on the risks of infection. Wireless charging can also bring safety benefits, as wired charging devices that come in contact with water can increase the chances of getting an electric shock. Wireless charging gets rid of that danger completely.

    Still, there are a few drawbacks to wireless charging. The first is speed. It takes a bit longer to charge devices wirelessly than it does if the device is plugged in. The process also requires more heat, so devices tend to get a bit hotter, which could create other safety issues. Also, since devices must be left on a special pad while charging, it is harder to operate them while they are powering up. This limitation may be gotten rid of in the future, as researchers are developing transmitters (发射器) that can charge several different devices in a room without the need to connect to a charging pad. Although wireless-charging technology may be far from perfect, it seems like a step in the right direction as we move towards a less-tangled future.

    American schools do not have separate classes for boys and girls. If boys want to cook or to sew, they can learn these things in classes that are no longer just for girls. If girls want to repair cars, they can now learn this in school. Most students like to have boys and girls on the same baseball team.

    Many boys and girls dress alike in school. They wear blue jeans and sport shirts. Some have long hair and some have short hair. Sometimes a boy has longer hair than a girl.

    Even the language is different. Students learn to say fire fighter instead of fireman, police officer instead of policeman, and letter carrier instead of mailman. A person does not need to be a man to fight a fire or to deliver the mail.

    Most people think that these changes are great. They give all people an equal chance to be happy and to do what they want to do with their lives. Fathers like to tell their sons that they can grow up to be president. Today, mothers can tell the same things to their daughters.

    The popularity of bicycling continues to rise, and it is no surprise. It's fun, healthy and eco-friendly. Maybe that's why there are 1.4 billion bicycles and only 400 million cars on roads worldwide today. Bikes can take you almost anywhere, and there is no fuel cost!

    Hop on a bicycle and ride around your neighborhood. You may discover something new in your community. Stopping and getting off a bike is easier than stopping and getting out of your car. In many communities, you can bike to work and benefit from exercise without polluting the environment. You don't even have to ride all the way. Folding bikes work well for workers who ride the train. Just fold the bike and take it with you.

    Have you ever thought about bicycling across a foreign country? It's a great way to experience another culture, see beautiful scenery and meet friendly people. Bicycle enthusiast Goran Kropp bicycled across not just one country but several. He rode a remarkable 11,000 km from his home in Sweden to Nepal and then climbed Mount Everest! And now, bicycling across a country to raise money for a charity or to advertise a cause is also popular.

    To encourage people to bike, many cities in Europe have established bike-share programs. In Paris, for example, thousands of bikes are parked at bike stations around the city. Users can rent bikes at any station. The first half-hour of use is free. After that, users pay a small fee. When they've finished riding, they simply park their bikes at any station. For people who don't want to drive, the bikes are an excellent alternative（替代品）to buses and taxis, which burn fuel and cause pollution.

    As a result of the success of bike plans in Europe, they're spreading to the US. Australia, China and other countries as well. Have you ever tried any shared bikes in your city?