Dreams do not occur during deep sleep. When people fall asleep, they are divided into deep sleep and light sleep, and the two periods alternate. During deep sleep, the cerebral cortex is completely relaxed, the body is completely relaxed, and the functional activities of the human brain are completely restored. Patients will not have any dreams during this period, and it is a normal physiological phenomenon for patients to dream. It is mainly during the light sleep period that some dreams occur, and the deep sleep and light sleep periods alternate for about 5-6 rounds every night. If the patient wakes up during the light sleep period, and it happens that the patient is still dreaming, he or she will have some memory of the dream. However, patients who wake up during deep sleep will not have any memory of the dream they had.