A 58-year-old man came to the clinic one day, accompanied by his wife, for screaming and hitting in his sleep. In the past, he had sought treatment from many places for shouting and hitting during sleep, but the diagnosis was unknown and the medication was ineffective. After arriving at my clinic, the patient was very restrained and said that he and his wife now sleep in separate beds, and that whenever he dreamed of doing any activity after falling asleep, his arms and legs would move, and when he dreamed of fighting, he would shout in bed, punch and kick, and his wife was injured many times by him, and even kicked out of bed by him. When he woke up, he did not know, only that he had nightmares. At first he didn’t believe it when he heard his wife’s description, until she retold what he was shouting and showed him the wounds on his body. This is a rare sleep behavior disorder called rapid eye movement sleep behavior disorder (RBD), and I have only diagnosed and treated a total of 16 cases in nearly 20 years of practice. RBD is a sleep behavior abnormality that occurs in REM sleep. When dreaming normally, the limbs do not move with the dream, regardless of the dream. Episodes of the disorder are characterized by dream-consistent motor activity. Although it can be seen at any age, it is most often seen in older men aged 60-70 years with violent dreams, and usually those with this disorder have a slightly higher incidence of Parkinson’s disease or dementia. Patients often cause self-injury or injury to co-sleepers. The behavior can last from a few seconds to several minutes, the violent behavior matches the content of the violent dream, and the dream in question can sometimes be recalled upon awakening. Diagnosis and treatment are often delayed because they are not recognized. For this disorder, clonazepam is an effective drug, and it can also be treated with nortriptyline. At the same time, attention needs to be paid to arranging the sleeping environment so that there is no tall or easily fallen furniture next to the bed. I once had a patient who jumped from the bed to under the bed during the onset of the disease at home and hit his head on the corner of the cabinet, resulting in a depressed skull fracture.