Dizziness or light-headedness when standing up

[Couch Potatoe]

In some people, particularly older people, blood pressure drops excessively when they sit or stand up (a condition called orthostatic or postural hypotension). Symptoms of faintness, light-headedness, dizziness, confusion, or blurred vision occur within seconds to a few minutes of standing (particularly after lying in bed or sitting for a long time) and resolve rapidly when the person lies down. However, some people fall, faint, or very rarely have a brief seizure. Symptoms are often more common and worse after people exercise, have consumed alcohol and/or a heavy meal, or are deficient in fluids (dehydration).
Some younger people experience similar symptoms upon standing but without having a drop in blood pressure. Often, their heart rate increases (tachycardia) more than normal upon standing, so this condition is called postural orthostatic tachycardia syndrome (POTS). The reason why such people feel dizzy despite having normal blood pressure is not yet clear.