As any younger brother will tell you, having a big brother involves a lot of walking in someone else's shadow, especially when you have a brother who is a typical example of "cool". For years I wanted to do everything my elder brother Tyson did, but no matter how hard I tried, I was always the neglected (被忽略的) one. My legs just weren't made to run like his. I could never play football or basketball well.

    I probably would have continued trying to keep up with him for the rest of my high school career, but when my family moved, everything changed. Tyson left for college, so I had to start at a new school all by myself. This new start gave me an opportunity to redefine myself and discover an entirely new version of "cool".

    I don't know what made me decide to try some new activities at the new school, but one day I chanced to show up for an after-school meeting of the Science Olympiad team. I had always been fascinated with chemistry, biology, and math, but since those interests hadn't fit Tyson's definition of "cool", I had never pursued them. On this day, for some reason, I did.

    As we organized teams, prepared resources and practiced answering questions, I felt more connected than I ever had to any sports team. I didn't feel as though I needed to keep up with anybody else; I was finally with peers who understood me. It was so good to feel accepted for what I'm good at. For the first time in my life, I actually felt cool. Now I know who I am! I'm Tyson's little brother, but that's only part of my identity. I'm a cool guy in my own way, too. I'm relieved to know that "cool" has a much broader definition than what I used to think.

    David Carter stands outside of the University of Texas' Austin campus every day, offering the same warm greeting to students who pass by. "Hello, my friend!"

    Carter, now 68, is a beggar who once attended the school from 1972 to L975. Then, he was involved in a crash and got serious injuries. He then had trouble with substance abuse and faced mental health challenges, leading him to drop out before completing his degree.

    "If I could change one thing about my past life, I would have stayed in school," Carter says. He says he knows an education can change someone's quality of life.

    Carter had to beg in the last few years fora simple reason. "I'm always flat broke," he said. While most people would walk right by a beggar, Ryan Chandler, a junior at the university, decided to stop and chat with Carter-and he learned a valuable lesson: You can't judge a book by its cover.

    "A lot of UT students see them as criminal vagrants (无业游民,乞丐) or think that they are dangerous or unfriendly, and that idea just isn't true," says Chandler.

    Chandler got to know Carter and saw his potential. "He completed 87 hours of course credits, which is enough for a degree for most people, but he just never finished," Chandler says.

    The student wrote a blog post about his new friend, and luckily, the right people heard about Carter and stepped in to help. The University of Texas readmitted Carter as a student, and a kind person who used to be a student UT offered to pay for Carter's tuition.

    "I want to be a student and I want to learn," Carter said. Since the course requirements have changed, Carter is far from having the amount of credits needed to graduate. But his friend knows he's willing to take up the challenge. "He is capable, he is ready, and he is dedicated to this," Chandler says.

    Why would human beings waste a third of their lives sleeping when they could be doing more important things like looking after their families or working? Some scientists believe sleeping helps recharge the body, while others think it is important for strengthening newly-formed memories. Now, there is new evidence which suggests that the purpose of sleep may be to forget some of the millions of new things we learn each day.

    The neurons in the human brain consist of fibers called dendrites (树突). These grow as we learn new things and connect the brain's cells to each other at contact points called synapses (突触). The larger the dendrites become and the more cells they connect, the more information we store.

    In 2018, Giulio Tononi and Chiara Cirelli, both biologists at the University of Wisconsin-Madison, suggested a new idea: The things our brains learn each day result in so many synapses that things start to get a little messy. Sleeping allows us to sort through (整理) the "noise" and dispense all the unnecessary information, leaving behind only the most important memories.

    Recently, the university's research has provided direct evidence to support the theory. The experiment involved analyzing 6,920 synapses in the brain shavings from two groups of mice over a four-year period; one group had been allowed to sleep, while the other had been kept awake and entertained with toys. The researchers discovered that the brain shavings of the sleeping mice had nearly 20 percent fewer synapses than those that had been kept awake and entertained.

    It was also evident during the study that the brain does not shave every synapse. 20% of neurons remained unchanged; these were most likely well-established memories. Therefore, although we may be sleeping to forget some of what we've learned, the brain "forgets" in a smart way.

    Most researchers believe clearing our brains is not the only purpose of sleep. Resting our minds and bodies has also been found to help with other biological functions like strengthening our immunity. Though scientists may never agree on a single reason, they are all sure of one thing－a good night's rest is essential for our health. So try and spend at least a third of your day sleeping!