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Why Do Some People See Stars When They Stand Up Too Fast?
为什么突然站起时眼前会冒金星？
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Those quick flashes of light are called phosphenes, and they result from temporary drops in blood pressure.
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When you stand suddenly, gravity pulls blood downward faster than your heart can pump it upward.
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This causes brief under-perfusion of the retina—the light-sensitive layer at the back of your eye.
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Without enough oxygen, retinal cells misfire, sending false signals that your brain interprets as light.
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The effect usually lasts only a few seconds and disappears once circulation stabilizes.
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Younger people experience it less often because their autonomic nervous system responds more quickly.
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Dehydration, low iron, or standing after lying down for hours increases the chance of seeing phosphenes.
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Unlike migraines or eye disease, this type of phosphene is harmless and requires no treatment.
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Athletes sometimes use controlled versions of this effect during training to improve vascular responsiveness.
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If dizziness or vision loss lasts longer than ten seconds, it’s wise to consult a healthcare provider.