Sometimes a person suddenly cries, but he or she does not know what the reason for crying is, usually due to depression. Because there are many unhappy and troublesome things repressed in the brain in the subconscious, usually can not touch, once experience a certain scene, or certain events, in the subconscious depression, repressed emotions may be released, resulting in sudden and inexplicable crying, usually related to this. If a similar situation often occurs, you must pay attention to it, go to the psychiatric psychology department to do the relevant depression test scale, and interview and talk with the doctor in person to see if you have a tendency to depression, the main manifestations of depression are insomnia, depressed mood, reduced interest, loss of hobbies, low self-esteem, slow thinking, memory loss, reduced volitional activity, as well as the risk of self-injury, self-harm, tendency, etc.