Dreams do not occur during deep sleep. When a person falls asleep, he or she is divided into deep sleep and light sleep, with the two periods alternating. During deep sleep, the cerebral cortex is in a state of complete relaxation, the body is also completely relaxed, and the functional activities of the human brain will be completely restored. Patients will not have any dreams during this period, and it is a normal physiological phenomenon for patients to dream. Mainly in the light sleep period will have some dreams, every night deep sleep and light sleep period about alternating 5-6 rounds. 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, if the patient wakes up during deep sleep, he or she will not have any memory of the dream.