Ancient people were superstitious. In the eyes of the ancients, dreams were a secret. If you tell your dream when you get up in the morning, it's equivalent to letting the cat out of the bag. Some people who know Yin and Yang by Feng Shui often say that "secrets can't be revealed", and revealing secrets is very unfavorable to them. Some old people also said that it is illegal to say dreams in the morning, which will dissolve the good luck of the day.
In addition, in ancient times, when farming was the main labor force, people also developed the life rule of "work at sunrise and rest at sunset", so they had no time to tell others their dreams in the morning. Maybe "don't talk about dreams early" is to avoid wasting a good opportunity to work early in the morning. The ancients also concluded that "a year's plan lies in spring, and a day's plan lies in the morning".
People are busy giving birth in the morning, saying that their dreams are not serious, and maybe no one has time to listen. Even if someone listens, once it is explained that the dream is unlucky, it will have a negative psychological impact, leading to a bad mood all day. For various reasons, the phrase "Don't talk about dreams too early" has spread.
According to the current scientific explanation, dreaming is a normal physiological and psychological activity of people, which mainly occurs in the fast wave sleep stage and is a means for people to release stress. When people sleep, the brain is resting, but the brain does not stop moving, but is running and thinking. These ideas are like arranging and combining our past memories in disorder, thus creating many interesting things. As a result, there was still some nerve excitement, which led to dreaming.