1 . Scientists recently discovered that our brains may be just as busy at night as they are during the day. While we sleep, our brains are doing much more than getting ready for the next day. Scientists found that the brain may be busy cleaning out harmful waste materials.
As with many studies, scientists turned to mice for help. They studied the mice brains as they slept and when they were awake. They saw that the brains of sleeping mice were hard at work.
Dr. Maiken led the study. The brain expert says our brains perform two very different jobs. It seems they have daytime jobs. Later they “moonlight” at a nighttime job. And this study says that is what our brains seem to be doing. “When we are awake, the brain cells are working very hard at processing all the information around us. When we are asleep, they work very, very hard at removing all the waste that builds up when we are awake.” The scientists say that the waste material includes poisons.
They also found that during sleep, the brain’s cells become smaller, which allows waste to be removed more successfully. Dr. Maiken says these poisons end up in the liver(肝脏). There, they are broken down and then removed from the body. “So we need to sleep because we have a cleaning system that removes many of the poisonous waste products from the brain.”
Dr. Maiken says the next step is to look for the process in human brains. She says the results show how important sleep is to health and fighting disease. The research may also one day lead to treatments to prevent or help fight mental disorders(精神疾病).
1. According to the scientists, when we sleep, our brains .| A．clean themselves | B．turn off for the night |
| C．process information | D．store energy for the next day |
| A．you work in the moonlight | B．you work hard |
| C．you work only at night | D．you have an extra job |
| A．breaking it down | B．sending it to the liver |
| C．building it up in order | D．removing it from the body |
| A．Opposed. | B．Indifferent. | C．Supportive. | D．Critical. |
