Yes. it is normal to hve lighheadedness when you suddenly stand up from a sitting or lying position. this is called orthostatic hypotension. this is a brief adjustemt of the body when there is sudden change in position usually caused by delayed constriction of the lower body blood vessels, which is normally required to maintain an adequate blood pressure when changing position to standing. As a result, blood pools in the blood vessels of the legs for a longer period, and less is returned to the heart, thereby leading to a reduced cardiac output, thus causing lighheadedness and dizziness. Mild orthostatic hypotension is common and can occur briefly in anyone, although it is prevalent in particular among the elderly, and those with known low blood pressure. Severe drops in blood pressure can lead to fainting with a possibility of injury.