Nightmares are caused by external physical stimulation and internal trauma. External causes: such as covering the nose and mouth with a quilt, lying on your back, pressing your chest with your hands, or uncoordinated and incorrect sleeping posture; For example, ghosts, foreign bodies press the bed and threaten themselves; So I want to struggle, to resist, to shout, but the part of the brain that commands the muscle movement and vocalization of hands and feet is in a state of inhibition, and I feel that I can't move, I have difficulty breathing, I am stuck in my neck, and I can't make a sound. Some physical discomfort, such as chronic tonsillitis, chronic rhinitis and chronic bronchitis, can also cause nightmares. (For reference only)