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Dear health-conscious friends,

You stand up.

And suddenly…

Your vision narrows.
Your ears ring.
The room tilts for a second.

Maybe you even grab the wall like you’re in a low-budget disaster movie.

Then — just as quickly — it passes.

So what just happened?

Did your brain briefly “switch off”?

Not quite.

But it did run low on fuel.

Here’s the simple physics.

When you’re lying or sitting, gravity isn’t fighting your circulation very much. Blood is evenly distributed.

The moment you stand, gravity pulls about 500–800 ml of blood down into your legs and abdomen.

That’s nearly a whole bottle of water suddenly leaving your brain.

For a few seconds, less blood = less oxygen = less glucose reaching your brain.

And your brain is dramatic.

Even tiny drops in supply cause symptoms fast:

Lightheadedness
Black spots
Tunnel vision
Nausea
Weak knees

It’s basically your brain saying:

“Excuse me. Where did my blood go?”

Normally, your body fixes this instantly.

Sensors in your neck and heart (baroreceptors) detect the pressure drop and trigger an automatic rescue plan:

Heart beats faster
Blood vessels tighten
Blood pressure rises
Flow returns to your brain

All within 5–10 seconds.

Crisis over.

You continue your day.

So why does dizziness happen sometimes?

Because the system isn’t perfect.

It struggles when you’re:

Dehydrated
Tired
Hungry
Iron deficient
On blood pressure meds
Pregnant
Recovering from illness
Standing up too fast

Less fluid in the tank means less backup when gravity steals some.

Doctors call this orthostatic hypotension — which is just fancy Latin for “your pressure drops when you stand.”

Sounds scary.

Usually isn’t.

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But here’s the important bit.

Occasional head rush? Normal.

Every single time?
Actually fainting?
Palpitations or chest pain?

That’s worth checking.

Because persistent symptoms can point to anemia, medication side effects, heart rhythm issues, or autonomic nervous system problems.

And those deserve proper evaluation — not just blaming “I stood up too fast.”

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Quick practical tips I give patients:

Drink more water than you think you need
Stand up slowly (sit → dangle legs → stand)
Eat regularly
Add salt if safe for you
Tense your leg muscles before standing
Don’t skip breakfast

Simple. Surprisingly effective.

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Your body is an elegant little engineering system.

Most days, it balances gravity beautifully.

And when you feel that brief dizzy wobble?

That’s just physics reminding you that you’re basically a water balloon with a brain.

Stay hydrated.
Stand gently.
Take care of that oxygen-hungry head of yours.

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Want more content like this? Check out our Youtube channel Askadoc!

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👩‍⚕️ Dr. Joanna​
​AskADoc4Advice — where medicine meets curiosity (and a little bit of weird).

Youtube Askadoc

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