Inexplicable upset may be caused by the following reasons: 1, it may be a problem of depression, depression patients are easy to depressed mood, happy, pessimistic about the future, disappointed, attention, memory loss. This is easy to appear irritable, anxiety, and even easy to provoke, temper and other symptoms. 2, may be caused by the problem of anxiety, anxiety may appear nervous, fearful and worried, always quiet, every day worrying and other symptoms. It is easy to become anxious, irritable and even grumpy with such emotional problems. 3. It may also be caused by physical diseases, such as disorders of sex hormone secretion, or menstrual disorders, hyperthyroidism and so on. These diseases are also easy to make people inexplicably always upset, anxious, and even always quarrel with people, fighting, etc. These reasons are more common.