Try this: For an entire day, forget about the clock. Eat when you're hungry and sleep when you're tired. What do you think will happen?

    You may be surprised to find that your day is much like most other days. You'll probably get hungry when you normally eat and tired when you normally sleep. Even though you don't know what time it is, your body does. These patterns of daily life are called circadian rhythms(生理节奏), and they are more than just habits. Inside our bodies are several clocklike systems that follow a roughly 24-hour cycle. Throughout the day and night, our inner clocks direct changes in temperature, body chemicals, hunger, sleepiness and more.

    Everyone's rhythms are different, which is why you might like to stay up late while your sister always wants to go to bed early. But on the whole, everyone is programmed to feel tired at night and energetic during the day. Learning about our body clocks may help scientists understand why problems arise when we act out of step with our circadian rhythms. For example, traveling across time zones can make people wake up in the middle of the night. Regularly staying up late can make kids do worse in tests.

    "There is a growing sense that when we eat and when we sleep are important parts of how healthy we are," says Steven Shea, director of the Sleep Disorders Program at Brigham and Women's Hospital in Boston.

    One way to learn about how our body clocks tick is to mess them up and see what happens. That's what neurologist(神经病学家)Frank Scheer and his workmates did in a recent study. Staying up night after night, their studies suggest, could make kids extra hungry and more likely to gain weight. And regularly sleeping too little, Scheer says, may be one cause of the recent increase in childhood obesity.

    You can use your smartphone to get pretty much anything delivered directly to your door almost immediately. The hardest part is the process of trying to work out if you should tip and if so, doing the quick math before you get to the door. And, you know well that you should tip about 15-20% at restaurants, but do the same rules apply to delivery drivers?

    The co-founder of Grubhub, Matt Maloney, pretty much set the standard for tipping delivery people in a Facebook post. He's a strong supporter of tipping, and Grubhub's website suggests a $5 or a 20% tip. Maloney also said this number should go up if you order during, say, a snowstorm.

    However, most other delivery services say on their websites that tipping is not required. Some services, like Door Dash, do suggest no tip on their checkout window. Many, like Amazon Prime Now, allow customers to change their tip amount after their delivery has been received to reflect the quality of service. These companies help customers save money but delivery drivers are upset. They deal with bad weather, heavy traffic, extreme tiredness, and more, all for a $1 tip. Many feel that if you'd tip your pizza boy or girl, you should tip your delivery driver.

    The Emily Post Institute (EPI)'s official suggestion falls in line with Maloney's: “10-15% of the bill, or $2-5 for pizza delivery depending on the size of the order and difficulty of delivery.”

    Just like servers in a restaurant, delivery drivers almost always rely on your tips for their income. Tipping is a long-standing cultural tradition in America. So, until drones (无人机) can deliver hot dogs straight to your door, it's best to tip the people riding through the city at all hours to bring you hot fresh food.

    People with an impulsive(冲动的) personality refer to those who tend to do things without considering the possible dangers or problems first. According to a new study by researchers at the University of Georgia, such people may be more likely to have food addiction. The study found that people exhibiting impulsive behavior weren't necessarily overweight, but impulsiveness was related to a direct relationship with food, and therefore, less healthy weight.

    Food addiction has been compared to addictive drug use. Studies have linked the dopamine (多巴胺) release that occurs after tasting delicious food to the dopamine release that happens when people consume other addictive substances.

    Impulsive behavior involves several personality traits (特点). Two of these traits, known as negative urgency and lack of perseverance, were particularly associated with food addiction and high BMI (身体质量指数) during the study.

    Negative urgency is characterized by the tendency to behave impulsively when experiencing negative emotions. Some people might drink alcohol or take drugs. For others, it could mean eating to feel better. Lack of perseverance is when a person has a hard time finishing hard or boring tasks. People with a lack of perseverance might have difficulty attempting to change addictive eating behavior, which could also cause obesity.

    "Impulsiveness might be one reason why some people eat in an addictive way despite motivation to lose weight," said Dr. Ashley Gearhardt, a clinical psychologist. He was involved in developing the Yale Food Addiction Scale in aid of those people. "We are theorizing that if food addiction is really a thing, then our measure, the Yale Food Addiction Scale, should be related to helping control impulsive action," said Gearhardt.

    Clinical psychologist Dr. James MacKillop, whose lab was conducting the study, believes that therapies(治疗，疗法)used to treat addictive drug behavior could help people who suffer from addictive eating habits.

    "Most of the programs for weight loss at this point focus on the most obvious things, which are clearly diet and exercise," MacKillop said. "It seems that managing strong desires to eat would naturally fit in with the skills a person would need to eat healthily."

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    Writing for AC is a great work opportunity for students, stay­at­home parents and freelance writers. You can work on your own time and provide papers, reviews, essays, etc. on any topic that you have interest in. This is a job you can do from anywhere—all you need is access to the Internet.

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    In addition to our own library of content, we have hundreds of partners (Partner Content Team) who work with AC to obtain high­quality. As such, there are lots of opportunities for our most talented and productive writers to accept "Partner Assignments" on an as­needed basis.

    If you're interested in accepting higher paying Partner Assignments, send us a link to your AC profile once you have provided at least five articles. We will review all articles and pass them along to our Partner Content Team. If selected, you will start receiving special paid assignments from us on a regular basis, which you are free to accept or ignore.

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    Any questions ? Email me: demel@asociatedcontent.com

    Exactly five years ago, on New Year's Eve, I was invited to a children's ball by a man high up in the business world, who had his connections, his circle of acquaintances, and his close friends. So it seemed as though the children's ball was merely an excuse for the parents to come together and discuss matters of interest to themselves, quite innocently and casually.

    I was an outsider, and as I had no special matters to express, I was able to spend the evening independently of the others. There was another gentleman present who had just stumbled upon (偶然遇到)this affair of domestic happiness，just like me. He was the first to attract my attention. His appearance was not that of a man of noble birth. He was tall, rather thin, very serious, and well dressed. Obviously he had no heart for the family celebration. The moment he went off into a corner by himself, the smile disappeared from his face, and his thick dark brows knitted into a frown. He knew no one except the host and showed every sign of being bored to death, though bravely keeping the role of thorough enjoyment to the end. Later I learned that he was a provincial, had come to the capital on some important business, had brought a letter of recommendation to our host, and our host had taken him under his protection, not at all with love. It was merely out of politeness that he had invited him to the children's ball.

    They did not play cards with him .They did not offer cigars. Thus , my gentleman , not knowing what to do with his hands , spent the evening stroking his whiskers(胡须). His whiskers were really fine, but he stroked them so eagerly that one got the feeling that the whiskers had come into the world first and afterwards the man, in order to stroke them.

Colorado's grays peak rises 14,278 feet above sea level, high enough that trees can't grow toward the top, though there are plenty of shrubs and rocks. It was in this unforgiving landform that Bev Wedelstedt was unlucky enough to get seriously injured in her left knee.

It was August 2018, and Wedelstedt, 56, was on her way back down the trail with three friends. A storm was brewing, and they were anxious to get off the mountain. When they approached a rocky drop of a couple of feet, Wedelstedt decided to leap. She landed on her left leg. Then she heard the snap. Every step after that was agony（剧痛）. Before long, she had to stop. As one friend ran down to get help, a number of other hikers, all strangers, attempted to help Wedelstedt down the narrow trail by walking on either side of her to support her weight, but that proved slow and dangerous. "One man was so close to the edge that I could see rocks falling down from where he stepped on them." Wedelstedt says.

Finally, one hiker, Matt, asked her, "How do you feel about a fireman's carry?" Before she knew it, he had lifted her over his shoulder. "Now, I'm not tiny," says Wedelstedt, a former college basketball star. Matt clearly couldn't carry her all the way down by himself. So six hikers and one of her friends took turns carrying her while she tried to make light of a difficult situation: "I told them I wanted to meet a lot of guys, but this isn't the way I wanted to do it." Three hours and two rock-strewn miles later, this human conveyor belt finally met the medics, who took Wedelstedt to the hospital.

She stayed in hospital for a period time. Now she has mostly recovered from her ill-fated hike, but Wedelstedt knows she'll never shake one thing from that day: the memory of the band of strangers who came to her rescue. "I'm still in awe."