Yes, we have all been there. You are sitting on your bed reading, most likely scrolling through your phone or watching something on your iPad, when someone calls you to go downstairs. You quickly push yourself off your bed, a bit too quickly, and you find yourself having to lean on the wall for support as your head aches with dizziness and your vision starts to become shaded with darkness. After a few seconds, you regather yourself and your vision becomes clear again.
Some of you may be thinking, well the answer is simple: when you stand up quickly, gravity loans all your blood to your legs for a moment, and your body needs time to pump it back up to your brain. That’s why everything suddenly feels like it’s tilting, your ears ring, and your vision fades a little – your brain isn’t getting enough blood yet.
Well, it isn’t that simple.
It may be a common phenomenon, but it has an uncommon name: orthostatic hypotension. It just means that when you shift from lying down or sitting, your blood pressure drops, and you momentarily feel a bit dizzy. This is because blood pools in your legs temporarily when you stand up, and it takes the body a moment to compensate by squeezing blood out of the large veins in your legs and revving up the heart. The dizziness may strike more after you eat a meal because digestion diverts blood flow and may lower your blood pressure.
For a moment, the brain is not supplied with enough blood and oxygen, and the oxygen supply for the light sensing tissue of the retina also falls. Since the retina requires a lot of oxygen to function properly, even a small dip in its supply can lead to vision problems which is why your vision darkens.
The process of maintaining stable pressure after standing up is controlled by the autonomic nervous system, a set of nerves that regulates involuntary bodily functions, such as heart rate, breathing and digestion.
However, the drop in blood pressure is detected by pressure-sensitive receptors in the arteries that supply blood to the brain and in the right atrium of the heart which is where blood flows into after delivering oxygen to the body. These activated receptors then trigger a body-wide response that stabilises the person’s blood pressure – blood vessels constrict, the muscles of the legs and abdomen contract and heart rate increases.
This does not usually cause noticeable effects. But in people who are dehydrated or experiencing an illness, like the flu, the drop in blood pressure may be more dramatic and might take longer to stabilise. People can also be prone to this dizziness if they take medication to reduce blood pressure, such as beta blockers.
According to Houston Methodist, some people can be prone to the symptoms when getting out of bed in the morning, since their blood pressure is typically low at that time, as well as when people drink alcohol or sweat a lot.
These short bouts of dizziness differ from chronic orthostatic hypotension, in which some individuals experience long-lasting or frequent loss of vision as well as balance, after standing. This condition can interfere with people’s daily lives and cause falls, fainting and car accidents, and it’s a risk factor for cardiovascular problems and kidney disease.
Dr Stephen Jurashek, an associate professor of medicine at Beth Israel Deaconess Medical Centre of Harvard Medical School, stated that “Postural hypotension may be particularly concerning if it persists beyond 3 minutes of standing”.
Depending on what causes the condition, orthostatic hypotension can be either primary or secondary, according to the National Institute of Neurological Disorders and Stroke. Primary orthostatic hypotension is rare and caused by impairments to the autonomic nervous system, such as those caused by nerve damage.
However, secondary postural hypotension, is where symptoms are caused by other medical conditions and so is much more common. This can be related to low heart rate (bradycardia), low blood sugar (hypoglycemia) and thyroid conditions.
I hope you learnt something new in this article and understand the deeper complexities of the topic that may have initially seemed quite simple.
So, some take aways are to get up more slowly, stay very hydrated, do a bit of light exercise in the morning to help get your blood moving and change your eating habits. This is because if dizziness strikes after meals, you should try eating smaller but more frequent meals.
See you next week for a new question and a new answer.
