Depression, also known as melancholia, is a type of mental illness mainly characterized by low mood. Patients with mild depression mainly appear as usual on the outside and experience pain on the inside, while patients with moderate depression may show depressed mood, sad face, sighing, low self-esteem, etc. Some patients are often accompanied by symptoms such as poor concentration, memory loss, slow reaction and insomnia. Patients with major depressive disorder will experience pessimism, despair, self-blame, hallucinations and delusions, loss of appetite, rapid weight loss, functional decline, and serious suicide attempts, and even suicidal behavior. Common symptoms of depression 1, mood disorders: patients are in a bad mood, mood depression, or anxiety, irritability, fidgeting; loss of interest in daily activities, loss of pleasure, the whole day sad face, worry; energy loss, often feel persistent fatigue; think there is no point in living, serious people feel desperate helpless, life is worse than death, life is like a year, some patients have the intention to end their lives. 2, slow thinking and self-evaluation: performance thinking ability decreases, patients often feel that thinking has become slower, the brain is not good, all aspects of the ability to decline, often self-guilt and self-blame, self-evaluation is too low, obviously study and work very well, but not satisfied with their own everything, will be some of their past small mistakes, small problems are said to be a heinous crime. 3. Psychomotor retardation: Patients have obvious inhibition of psychomotor activity, difficulty in association, reduced speech, low voice, and slow action. Sometimes they live alone behind closed doors, indifferent to family, unable to take care of household chores, and in severe cases, they do not speak, do not move, do not eat, do not drink. 4, other symptoms: patients often appear appetite, libido significantly reduced, significantly thin, weight loss; insomnia is serious, most sleep difficulties, nightmares easy to wake up, waking up early, unable to sleep after waking, depression often shows the morning heavy night light pattern.