what’s happens physiologically when you stand up too fast and feel numb and lightheaded?
In: Biology
This is a sign of low blood pressure. When you sit down or even more when laying down your heart actually reduces the pressure it pumps at and the blood vessels in your legs relaxes to allow more blood which also reduce blood pressure. This is because you need less blood pressure to get blood flowing to your head. If you stand up quickly then suddenly the blood is going to flow to your legs instead of your brain. It takes some time for your heart to pump with more pressure and for the blood vessels in your legs to restrict blood flow again as this is very simple reactive actions. So blood flow to your brain is going to be reduced for a bit. This is what causes you to become lightheaded. You may also lose balance or sight for a short time. In extreme cases you may also pass out. If you sit down again this will fix it and you can get up more slowly.
This only happens if you have low blood pressure. This can be caused by a number of things. For example if you are sleeping you have naturally low blood pressure so it is not uncommon for healthy people to wake up and quickly stand up just to get lightheaded and even lose their eyesight for a moment. But it can also be due to being dehydrated as this also causes low blood pressure. Blood pressure is also affected by general stress or being burned out. You may also have a disease that causes your blood pressure to become too low. So this is something that you should pay a bit of attention to and tell your doctor about if it happens a lot.
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