Our body clock, or natural body rhythm, influences our energy and alertness. Paying attention to it can help us choose the suitable time of the day when we best perform specific tasks.

    The reality, however, is that most of us organize the time around work demands, school deadlines, commuting or social events. Doing whatever the body feels like doing is a luxury in today's fast-paced modern society.

    But that doesn't mean it isn't worth trying. Obeying our body clock has significant health benefits. Disrupting our natural body rhythm, on the other hand, has been linked to problems such as depression, obesity, or headache, says Steve Key, a biology professor.

    When the body clock can synchronize (使…同步) the rhythms of its natural processes, it “gives us an advantage in daily life”, says Key.

    According to him, when it comes to cognitive (认知的) work, most adults perform best in the late morning. As our body temperature starts to rise just before awakening in the morning and continues to increase until midday, our memory, alertness and concentration gradually improve.

    However, he adds, our ability to concentrate typically starts to decrease soon thereafter. Most of us are more easily distracted (分心) between noon and 4 pm.

    Alertness also tends to fall after eating a meal and sleepiness tends to peak around 2 pm, making that a good time for a nap.

    Surprisingly, tiredness may increase our creative powers. For most adults, problems that require open-ended thinking are often best dealt with in the evening when they are tired, according to a study in the journal Thinking & Reasoning.

    When choosing a time of the day to exercise, paying attention to your body clock can improve results. Physical performance is usually best from about 3 to 6 pm, says Michael Smolensky, a professor of biomedical engineering.

    Of course, not everyone's body clock is the same, making it even harder to synchronize natural rhythms with daily plans.

    Shlander is a man from space. He thinks the people and things on the earth are very strange. He is now writing a letter to his friend at home. Here is part of his letter. Read it and answer the questions.

    Now I am in a strange world. It is very nice. There are many new things here. There are many earth monsters (怪物) here, too. The earth monsters look very funny. They have just one head, two arms and two legs. They have thin black strings(细绳) on their heads. Some earth monsters have brown or yellow strings. The earth monsters have a hole in their faces. Every day, they put nice things and balls from the trees into the hole. They put water into the hole, too. The earth monsters do not walk very fast. They move from place to place in tin boxes.

    At night, the earth monsters like to look at a square window box. This box has very small earth monsters in it.

    An Oceans Vacuum

    There's a collection of plastic trash in the middle of the Pacific Ocean. It's bigger than Texas-and growing. The way to clean it up now is to catch it with nets. That is both costly and slow. Instead, the Ocean Cleanup Project proposes 62-mile-long floating barriers that would use natural currents to trap trash. If next year's trials succeed, a full cleanup operation would aim to start in 2020. It could reduce the trash by 42% over 10 years.

    Easy-On Shoes

    In 2012, Mathew Walzer, a high school student with a disability, sent a note to Nike. “My dream is to go to college,” he wrote, “without having to worry about someone coming to tie my shoes every day.” Nike assigned a design team to the challenge. This year, they came out with their solution: the FlyEase. The basketball shoe can be fastened with one hand. A pair of Nike FlyEase shoes sells for $130.

    An Airport for Drones(无人机)

    As Amazon, Google, and others get ready for drone delivery service, there is one big question: what kinds of home bases will their drones have? Rwanda, in Africa, may have the answer. There, workers will soon start work on three “drone ports”. The goal is to make it easier to transport food, medical supplies, electronics, and other goods through the hilly countryside. Construction is set to be completed in 2020.

    When Boris left school, he could not find a job. He tried hard and he wrote letters to many companies until he could not afford to buy any more stamps. Boris began to lose his confidence, then depressed. Still he went on trying and still he failed. He began to think that he had no future at all.

    “Why don't you start your own business?” one of his uncles told him. “The world is a money-locker. You'd better find a way of opening it.”

    “But what can I do?”

    “Get out and have a look round.” advised his uncle. “See what people want; then give it to them, and they will pay for it.”

    Boris began to cycle around the town and found a suitable piece of waste ground in the end. Then he set up his business as a cycle repairer. He worked hard, made friends with his customers and gradually managed to win his good fame. A few months later, he found that he had more work than he could deal with by himself. He found a number of empty shops but they were all no good: in the wrong position, too expensive or with some other problems. But at long last, he managed to find an empty shop in a new place where there were plenty of customers but no competition.

    Boris and his assistant taught themselves how to repair motor-cycles. Slowly but surely the profits increased and the business developed. At last, Boris had managed to open the money-locker and found bank notes and gold coins inside.

Maths and Music

    An excellent way to kill a conversation is to say you are a mathematician. Tell others you are also a musician, however, and they will be hooked. Although there are obvious similarities between mathematical and musical activity, there is no direct evidence for the kind of magical connection many people seem to believe in.

    I'm partly referring here to the "Mozart effect", where children who have been played Mozart compositions are supposedly more intelligent, including at maths, than other children. It is not hard to see why such a theory would be popular: we would all like to become better at maths without putting in any effort. But the conclusions of the experiment that expressed the belief in the Mozart effect were much more modest. If you want your brain to work better, you clearly have to put in hard work. As for learning to play the piano, it also takes effort.

    Surely a connection is quite reasonable. Both maths and music deal with abstract structures, so if you become good at one, then it is likely that you become good at something more general that helps you with the other. If this is correct, it would show a connection between mathematical and musical ability. It would be more like the connection between abilities at football and tennis. To become better at one, you need to improve your fitness and coordination (协调). That makes you better at sport and probably helps with the other.

    Abstract structures don't exist only in maths and music. If you learn a language then you need to understand its abstract structures like grammar. Yet we don't hear people asking about a connection between mathematical and linguistic (语言的) ability. Maybe this is because grammar feels mathematical, so it wouldn't be surprising that mathematicians were better at learning grammar. Music, however, is strongly tied up with feelings and can be enjoyed even by people who know little about it. As such, it seems different from maths, so there wouldn't be any connection between the two.

    Let's see how we solve problems of the "A is to B as C is to D" kind. These appear in intelligence tests but they are also central to both music and maths. Consider the opening of Mozart's Eine Kleine Nachtmusik (小夜曲). The second phrase is a clear answer to the first. The listener thinks: "The first phrase goes upward and uses the notes of a G major chord (和弦); what would be the corresponding phrase that goes downward and uses the notes of a D7?" Music is full of puzzles like this. If you are good at them, expectations will constantly be set up in your mind. The best moments surprise you by being unexpected, but we need the expectations in the first place.