As the saying goes, “No man is good for a hundred days, no flower is good for a hundred days”. This life in the world, who all hope that their life can be smooth sailing, everything is successful. However, this can only be a good wish, in real life is often “life is not as good as nine out of ten”. “The most important thing is that you have to be able to get a good idea of what you want to do. It is like a river of spring water flowing to the east”, the poets of the past and present express the most is the inner sorrow. We all have bad times in our lives, and we all experience melancholy at some point in our lives. “It is common for people to cheer and cry when they encounter happy events and sad events. For example, when the sudden death of a loved one, there is a short period of time to feel sad, this is normal. But if the melancholy, sad mood is too strong, or long time can not get out of the melancholy, that is the pathological emotional reaction, that may be suffering from depression, that can not be treated idly. The prevalence of depression is very high, and the lifetime prevalence of major depression in the general community population is 17.1%, which is 2-3 times higher in women than in men, and the lifetime prevalence is roughly one quarter in women and one eighth in men. Depression has significant adverse effects on an individual’s mental and physical health, social interactions, occupational ability, and somatic functioning. According to WHO, depressive disorders ranked 5th in the global burden of disease in 1990, and it is predicted that depressive disorders will become the second largest source of disease burden after coronary heart disease by 2020. Most importantly, depressed patients have a higher risk of suicide, self-injury, and even killing their loved ones. 2/3 of depressed patients have had suicidal thoughts and behaviors, and 15%-25% of depressed patients eventually succeed in committing suicide. Therefore, it is very important to detect and treat depression early. How to detect depression early? The following five major signals when alert. 1. Depressed mood signal. This is the most obvious clinical manifestation of early depression, manifested as listlessness, depression, a decline in interest, loneliness, sadness, pain or depression. Patients feel helpless, hopeless, self-guilt and self-blame, and even the thought and behavior of light-heartedness. 2. Loss of pleasure and diminished interest. This is the second common background symptom of depression. People with loss of pleasure do not experience happiness even when something happy happens. They are not happy about the good weather, being praised, winning in a game or an unexpected fortune, and they do not enjoy the pleasure of doing their favorite activities. Diminished interest, manifested in all aspects of work life, pastimes and entertainment, no longer enjoy the things they used to be interested in, and lose the expected pleasure and attention. 3. Lack of motivation signals. Most patients with early depression are able to persist in their study work and social interpersonal, but there is a clear lack of initiative and motivation, the patient feels no energy, as if the fountain of life will dry up, he does not want to do anything, there is no motivation at all, even if they can barely do something, they feel overwhelmed. Some patients’ language and behavior seem slow, hesitant, breathless, lethargic, feel no desire for work, study, social life, sports, etc., often avoiding, preferring to be alone. 4.Signal of physical symptoms. In the early stage of depression, there are often various symptoms of physical discomfort that are variable and unexplained, and in some cases, even if abnormalities are detected, the cause of the discomfort or its severity cannot be explained. Common discomforts include back pain, limb tenderness, stomach pain and bloating, nausea and anorexia, panic attacks and palpitations, weight loss, and decreased libido. Many patients therefore repeatedly go to major hospitals for examination, but the treatment is not effective. 5, sleep disorder signal. It can be manifested as difficulty in falling asleep, shallow sleep, dreamy and easy to wake up, typically early awakening. Patients often lie in bed for hours without being able to sleep, often haunted by painful thoughts, confusing and anxious nightmares, waking up early in the morning with unclear mind, sleepiness and fatigue. However, some patients also show excessive sleepiness, lazy sleep and refusal to get up, and some may stay in bed all day. The more obvious the depressive symptoms are, the more the above-mentioned signals will appear and the longer the duration will be. In addition, there are many psychological scales that can help us to assess the presence of depression.