What is a Dream

A dream is a psychological activity that occurs during sleep. The mental activities in dreams reflect objective things in the human brain, just like the mental activities during wakefulness. The bizarre dream scenarios in dreams are illusions caused by the stimulation of various objective things when the brain's consciousness is unclear during sleep. For example, the palpitations experienced when awake and having a rapid heartbeat can turn into eerie nightmares of being chased in dreams. The feeling of heart suspension or sinking caused by a slow or premature heartbeat when awake can transform into strange nightmares of floating or falling in dreams.

In dreams, one often experiences subtle physiological symptoms that are not easily felt when awake. This is because the stimulation from external objective things decreases relative to sleep, while the stimulation from internal objective things increases.

Dreams are closely related to a person's social environment, psychological factors, and physical condition. In Qian Zhongshu's "Zhang Zhan's Commentary on the Book of Liezi," there is a detailed discussion on the interpretation of dreams in ancient China, proposing that dreams may arise from "thoughts" or "causes." "Thought dreams" refer to dreams formed by the sensations of the internal body due to external stimuli.