So there you are, crouched low on the ground,tying your shoe or inspecting some interesting bit of trash or sidewalk art orspring flower… and everything’s cool until you stand up too fast. Then comes the headrush. Suddenly you’re all dizzy and feeling likeyou might black out, and just as you think you’re gonna fall over, everything’s backto normal, and you’re left wondering what the heck just happened? Well, probably your blood pressure droppedis what happened.

Your blood pressure will vary a little throughoutthe day, like if you’re stressed or relaxing, running or sleeping, but in general it existswithin an average range. That said, individual’s normal ranges alsovary for example, athletes typically have lower blood pressure than overweight smokers and what’s normal for you might be considered low or high for me. We’ve all heard how elevated blood pressure,or hypertension, can be dangerous it puts extra strain on the heart, and can causearterial walls to leak or rupture but low blood pressure, or hypotension, can also causeproblems.

Like dizziness and fainting. Lots of conditions can lead to temporary orchronic low pressure, like pregnancy, dehydration, anemia, or taking various medications. But there are a specific types of hypotension,too, when it’s specifically associated with things like eating or nerve damage. When you stand up too fast and get that wobbly,headrushy sudden drop in blood pressure? s call that orthostatic, or posturalhypotension. It happens because even though your bloodkeeps circulating no matter what position

you’re in, when you stand, gravity causessome of the blood to collect in your legs. Your body is supposed to combat this by constrictingblood vessels and ramping up your heart rate effectively increasing the pressure tohelp keep enough of your blood flowing through important places like your brain. But sometimes when you jump up too quickly,that sudden change in blood flow and drop in pressure can strike before your circulatorysystem has a chance to recalibrate, and now you’re seeing stars and groping for balance which is basically your desperate brain’s way of telling you it needs more oxygen.

Usually it only takes a few seconds for theadjusted blood pressure to kick in, but if that initial drop is too extreme, you couldactually faint. If you’re feeling faint all the time, especiallywhen you haven’t just stood up quickly … well, you might want to get that checked out. Butlots of people get head rushes now and then, and it isn’t a big deal. Still, if you’d rather avoid the dizziness,just remember to take your time standing up the next time you tie your shoes. Thanks to patreon patron Alexa Singer forasking this question, and thanks to all our

patrons, who keep these answers coming. Ifyou’d like to submit a question to be answered, just go to patreon scishow. And don’tforget to go to scishow and subscribe!.

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