When we stand up from sitting or lying down, our blood vessels respond to gravity by narrowing to prevent our blood pressure falling. This ensures a steady supply of oxygenated blood to the brain.
Orthostatic hypotension is a form of low blood pressure. It happens when the blood vessels do not constrict (tighten) as you stand up. It is usually a symptom of an underlying disorder rather than a disease in itself. The condition is also known as postural hypotension.
Everyone is likely to experience a mild form of postural hypotension at some time. It’s the lightheaded feeling you may get if you leap out of bed very quickly.
Orthostatic hypotension — also called postural hypotension — is a form of low blood pressure that happens when you stand up from sitting or lying down. Orthostatic hypotension can make you feel dizzy or lightheaded, and maybe even cause you to faint.
Orthostatic hypotension may be mild, and episodes can last for less than a few minutes. However, long-lasting orthostatic hypotension can signal more-serious problems, so it's important to see a doctor if you frequently feel lightheaded when standing up.
Occasional (acute) orthostatic hypotension is usually caused by something obvious, such as dehydration or lengthy bed rest, and is easily treated. Chronic orthostatic hypotension is usually a sign of another health problem, so treatment varies.
Dizziness is a word that is often used to describe two different feelings. It is important to know exactly what you mean when you say "I feel dizzy," because it can help you and your doctor narrow down the list of possible problems.
Lightheadedness is a feeling that you are about to faint or "pass out." Although you may feel dizzy, you do not feel as though you or your surroundings are moving. Lightheadedness often goes away or improves when you lie down. If lightheadedness gets worse, it can lead to a feeling of almost fainting or a fainting spell (syncope). You may sometimes feel nauseated or vomit when you are lightheaded.
Vertigo is a feeling that you or your surroundings are moving when there is no actual movement. You may feel as though you are off balance, spinning, whirling, falling, or tilting. When you have severe vertigo, you may feel very nauseated or vomit. You may have trouble walking or standing, and you may lose your balance and fall.
Although dizziness can occur in people of any age, it is more common among older adults. A fear of dizziness can cause older adults to limit their physical and social activities. Dizziness can also lead to falls and other injuries.
Lightheadedness
It is common to feel lightheaded from time to time. Brief episodes of lightheadedness are not usually the result of a serious problem. Lightheadedness often is caused by a momentary drop in blood pressure and blood flow to your head that occurs when you get up too quickly from a seated or lying position (orthostatic hypotension). Ongoing lightheadedness may mean you have a more serious problem that needs to be evaluated.
