资料：Dream is a story that a person watches or even takes part in during sleep. Dream events are imaginary, but they are related to real experiences and needs in the dreamer"s life. They seem real while they are takingplace. Some dreams are pleasant, others are annoying, and still others are frightening. Everyone dreams, but some persons never recall dreaming. Others remember only a little about a dream they had just before awakening and nothing about earlier dreams. No one recalls all his dreams. Dreams involve little logical thought. In most dreams, the dreamer cannot control what happens to him. The story may be confusing, and things happen that would not happen in real life. People see in most dreams, but they may also hear, smell, touch, and taste in their dreams. Most dreams occur in color. But persons who have been blind since birth do not see at all in dreams. Dreams are a product of the sleeper"s mind. They include events and feelings that he has experienced. Most dreams are related to events of the day before the dream and strong wishes of the dreamer. Many minor incidents of the hours before sleep appear in dreams. Deep wishes or fears-especially those held since childhood-often appear in dream. and many dreams fulfil such wishes. Events in the sleeper"s surrounding-a loud noise, for example, may become part of a dream, but they do not cause dreams. Some dreams involve deep feeling that a person may realize he has. Psychiatrists often use material from a patient’s dreams to help the person understand himself better. Dreaming may help maintain good learning ability, memory, and emotional adjustment. People who get plenty of sleep-but are awakened each time they begin to dream-become anxious and restless. This passage is mainly about______.