Unexplained fainting is medically known as syncope, a state of transient loss of consciousness caused by insufficient blood supply to the brain. Patients will suddenly fall to the ground, and may also be accompanied by dizziness, nausea and other manifestations, often sudden onset, can recover on their own, recovery generally does not leave after-effects. Syncope is caused by a variety of reasons, which can be broadly divided into physiological factors, pathological factors and drug factors. Physiological factors: 1, environmental factors: long-term dry, crowded, stuffy environment may cause vasovagal syncope; 2, lifestyle: prolonged standing, excessive fatigue, stress, hunger, etc., may lead to syncope. Second, pathological factors: 1, reflex syncope: due to abnormal blood pressure regulation, autonomic insufficiency, etc., causing the patient’s heart rate to slow down, the amount of cardiac blood return and cardiac output to decrease, blood pressure to reduce, resulting in syncope due to insufficient blood supply to the brain; 2, postural hypotensive syncope: sudden change of position, sudden sitting up while lying or squatting and sudden standing up, etc., may easily lead to insufficient blood supply to the brain and induce syncope; 3 Cardiogenic syncope: mainly caused by cardiac arrhythmia or cardiovascular disease, because of the reduction of cardiac blood displacement or suspension of blood displacement leads to cerebral ischemia, thus inducing syncope; 4, other: hypoglycemia, hypotension, cerebrovascular disease, etc., can also cause insufficient blood supply to brain tissue, leading to syncope. Third, drug factors: such as the use of some sedatives, sleeping pills, narcotics, etc., will inhibit the vasomotor center caused by postural hypotension, resulting in syncope. Generally, after finding syncope, it is recommended to go to the hospital in time to improve blood pressure, cranial CT, cardiac ultrasound and other examinations, first of all, it is necessary to exclude the disease factors leading to syncope, and if it is caused by a certain disease, it is necessary to actively treat the cause.