STANDING up too fast can often make you feel dizzy — but sometimes it’s a sign you should see a doctor.
Head rush is a common occurrence and is not something you should necessarily be worried about.
GettyStanding up too fast can often make you feel dizzy because of a rapid drop in blood pressure[/caption]
The reaction — known medically as postural or orthostatic hypotension — is caused by a rapid change in how your body is positioned.
It can make you lose your balance or your vision to go black temporarily.
This is because of a temporary drop in blood pressure that reduces the supply of blood and oxygen to the brain.
Blood supply to the retina also falls, causing the darkness in vision.
Dr Stephen Juraschek, of Harvard Medical School, told Live Science: “When people stand up, about 300 to 800cm cubed of blood gets pulled in the legs, leading to a temporary drop in blood pressure.”
This drop is detected by your arteries, triggering a whole-body response to stabilise blood pressure.
Your blood vessels constrict, muscles in your legs and tummy contract and heart rate increases.
Normally this doesn’t cause any obvious symptoms, but you can take longer to stabilise if you are dehydrated or feeling ill.
However, it can be a problem if you regularly experience it.
Dr Juraschek said: “Postural hypotension may be particularly concerning if it persists beyond 3 minutes of standing.”
This could be a sign of nerve damage in rare cases, which is impacting the autonomic nervous system.
It could also mean you are suffering a low heart rate, low blood sugar or some thyroid conditions, according to Mayo Clinic.
Other linked conditions include heart failure, vitamin B12 deficiency, alcoholism, Parkinson’s, Alzheimer’s, anaemia and atherosclerosis, according to the NHS.
If you are concerned about symptoms, the health service recommends you have your blood pressure taken by your GP.