The common clinical causes of feeling tired and fatigue all the time are sleep deprivation, depression, anemia, respiratory diseases, heart diseases, pregnancy and so on. 1. Lack of sleep: people who sleep less or have poorer quality of sleep, their brain and other tissues can not get enough rest and recovery, the clinical manifestations of generalized weakness, fatigue, mental depression, and so on. 2. Depression: People suffering from depression usually have a more obvious sense of fatigue, as well as disinterest in things around them, memory loss, lack of pleasure, and so on. 3. Anemia: people suffering from this disease have insufficient red blood cells to supply oxygen to the tissues and organs, with clinical manifestations such as weakness, fatigue, dizziness, and so on. 4. Respiratory diseases: clinically common are chronic obstructive pulmonary disease (COPD), tuberculosis and so on, COPD people will have more obvious symptoms of dyspnea when they are in serious condition; there are also people suffering from tuberculosis, whose energy consumption is large, and frequent fatigue is easy to occur if the nutrients they consume are insufficient. 5. Heart disease: this kind of disease is common, such as heart failure, people with heart failure, heart muscle damage is more serious, when the condition is more serious, appropriate activities or rest will appear obvious dyspnea, generalized fatigue and other symptoms. 6. Pregnancy: After pregnancy, the trophoblast cells of the embryo will secrete a large amount of human chorionic gonadotropin, which will cause pregnancy-related reactions, mainly vomiting, poor mental health, loss of appetite, etc. This is a normal physiological reaction. If it is a disease factor, it is recommended to go to the hospital to improve the relevant examination to clarify the cause of the disease, and carry out targeted treatment.