Dreaming itself is a normal natural physiological phenomenon, nightmares at night is mostly related to mental tension, improper sleeping posture, in addition to bad dietary habits, drug factors, some psychological diseases, etc. will also appear nightmares. 1, mental psychological factors: if the work pressure during the day, the spirit is too nervous, there may be nightmares at night, in addition is the recent may have experienced some bad things, such as The death of relatives, car accidents, etc., the spirit is stimulated, there will also be nightmares; 2, improper sleeping position: some people sleep with the mouth and nose covered by a blanket or bedding, chest by the arm or certain items of pressure, will also induce nightmares; 3, bad eating habits: if you eat too much before going to bed at night, the bulging stomach and intestines will compress the surrounding organs, so that the brain cells are active, it will induce the appearance of nightmares; 4 , drug factors: some drug adverse reactions in sleep disorders, nightmares, such as antidepressants, antiviral drugs, antibiotics, etc.; 5, psychological diseases: such as neurasthenia, anxiety, hysteria, obsessive-compulsive neurosis, depression, etc., patients will be prone to nightmares at night; 6, other: cerebrovascular disease, endocrine disorders, etc., can also cause patients to have nightmares at night. If the nightmares are not frequent and have no significant impact on sleep quality and daytime work life, there is usually no need to worry too much, try to relax the mood can be relieved. If the nightmares are frequent, causing emotional instability, low work efficiency, daytime lethargy, seriously affecting the usual work, study and life, you need to pay attention to it, it is recommended to seek medical attention in time to avoid delaying the disease.