Weak legs, weakness, dizziness, and always wanting to sleep are considered to be cerebral blood supply insufficiency. If middle-aged and elderly people have a lot of diarrhea, vomiting and sweating for a long time, it will cause hypovolemia, hypoperfusion of the brain and insufficient cerebral blood supply, and patients mainly have the above symptoms when the blood supply to the cerebellar brainstem is insufficient. In addition, it can also be seen in severe hypotension, blood pressure drop too fast patients, blood pressure drop too fast, mainly seen in postural hypotension, postural hypotension is a kind of generalized autonomic dysfunction disease, the patient’s prone blood pressure is higher, the sitting position or standing position blood pressure is low, in the case of the patient from the prone position to the upright position or the sitting position when the movement is too violent, it will cause a transient drop in blood pressure, cerebral blood supply is insufficient. Severe blood pressure drop can be seen in patients with heart disease, such as severe arrhythmia, which can easily cause a decrease in the pumping volume of the heart, and relative cerebral blood supply insufficiency.