It’s late in the evening: time to close the book and turn off the computer. You’re done for the day. What you may not realize, however, is that the learning process actually continues—in your dreams.

    It might sound like science fiction, but researchers are increasingly focusing on the relationship between the knowledge and skills our brains absorb during the day and the fragmented, often bizarre imaginings they generate at night. Scientists have found that dreaming about a task we’ve learned is associated with improved performance in that activity (suggesting that there’s some truth to the popular notion that we’re “getting” a foreign language once we begin dreaming in it). What’s more, researchers are coming to recognize that dreaming is an essential part of understanding, organizing and retaining what we learn.

    While we sleep, research indicates, the brain replays the patterns of activity it experienced during waking hours, allowing us to enter what one psychologist calls a neural (神经的) virtual reality. A vivid example of such replay can be seen in a video researchers made recently about sleep disorders. They taught a series of dance moves to a group of patients with conditions like sleepwalking, in which the sleeper engages in the kind of physical movement that does not normally occur during sleep. They then videotaped the subjects as they slept. Lying in bed, eyes closed, one female patient on the tape performs the dance moves she learned earlier.

    This shows that while our bodies are at rest, our brains are drawing what’s important from the information and events we’ve recently encountered, then integrating that data into the vast store of what we already know. In a 2010 study, researchers at Harvard Medical School reported that college students who dreamed about a computer maze (迷宫) task they had learned showed a 10-fold improvement in their ability to find their way through the maze compared with participants who did not dream about the task.

    Robert Stickgold, one of the Harvard researchers, suggests that studying right before bedtime or taking a nap following a study session in the afternoon might increase the odds of dreaming about the material. Think about that as your head hits the pillow tonight.

解析：D。根据题干中的when one enters a dream state可定位至原文的第三段首句。该句提到，研究表明，我们在睡觉的时候，大脑会回放它在我们清醒时所经历的活动模式。D项与此内容一致，其中的once again experiences对应定位句中的replays，learning activities of the day对应定位句中的activity it experienced during waking hours，故D项为正确答案。

错项排除：原文第三段中提到了梦游症患者会在睡梦中作出反常的举动，但这仅限于此类患者，并不是每个人都会做的事情，故A项排除。原文第三段第一句后半部分提到，人们在睡觉时会进入“神经虚拟现实”状态（neural virtual reality），并没有说大脑的神经活动会变得更加活跃，这里的“虚拟现实”与虚拟现实电子游戏无关，原文中没有提及B项中的activity和C项中的video games，故B项和C项可排除。