Easy dizziness, blackness before the eyes, most of them are due to cerebral hypoxia, ischemia, commonly known as cerebral blood supply is insufficient performance, is a wide range of cerebral tissue hypoxia, most of them will be caused by the following three reasons: 1, low blood pressure: the upright position will make the basic blood pressure is low in the patient appeared to have a sudden drop in blood pressure, caused by cerebral blood supply of the recession, reduction, blackmont, dizziness symptoms; 2, hypoglycemia: the hot weather Low blood sugar: when walking for a long time in hot weather, the state of hunger can lead to hypoglycemia, which will also appear blackout, dizziness; 3, more serious underlying heart disease: arrhythmia, coronary artery disease, myocardial ischemia manifestations, when certain reasons arise, such as emotional excitement, straining to defecate, walking for a long time, dizziness, blackout will also occur. If the symptoms of heart disease patients need to go to the hospital as soon as possible. The first two kinds of patients need to try to take the lying position and as soon as possible to lift the trigger, low blood sugar can be a small amount of food, low blood pressure by lying down to rest, can be lifted.