Sitting up dizziness is mainly due to the change in blood pressure brought about by the change in position, resulting in the performance of decreased or insufficient blood supply to the brain, which is actually a normal physiological reaction in clinical practice. If squatting or lying for too long, when suddenly sitting or standing, there is a significant drop in blood pressure within 1-3 minutes. Postural hypotension is diagnosed if the drop in blood pressure exceeds 20/10 mmHg, or if the blood pressure is directly below 90/60 mmHg. Most patients will present with dizziness or brief blackouts, and in severe cases, syncope. By this time the clinical phase of the disease has been reached and most drops do not exceed 20/10 mmHg, but a drop in blood pressure will be seen and will manifest as transient dizziness. It is also important to be alert to the possibility that especially young women can be anemic. If you are usually a vegetarian, or a partial eater, or have a heavy menstrual flow, have your blood checked to see if you are anemic.