Further explanation seems unnecessary.
You don’t necessarily see stars when you get dizzy. With classical vertigo (dizziness) caused by a signal from your inner ear that doesn’t match other sensory input, the world just seems to be turning around you but you don’t see stars.
Seeing stars is a manifestation of insufficient blood getting to your visual cortex (the back of the brain where you process information from your eyes) and this happens just before you faint or are about to faint, such as when you stand up too quickly after spending 18 hours in bed witht he flu. You can call this “dizziness” rather than “feeling faint” but I think that most of the time when someone says they are dizzy they mean that the world seems to be turning around them, not that they are seeing stars.
I see stars after i cough. The not-enough-blood explanation doesn’t feel like it covers that, but my WAG why this happens is the retina being jiggled about a bit from the cough.
Ok, maybe dizziness wasn’t the best word.
Not enough blood to visual cortex. Got that. You get the stars from straining yourself too, but I could buy that the blood somehow is low on oxygen then.
Not quite as easy-to-find-out or meaningful-to-know is - why do you see STARS moving in this peculiar way? Why not… black dots? Or lessened field of vision? (I get this sometimes instead)
I just had stars circling around so I felt like asking. It’s sort of a fun experience anyhow
It’s pressure on your eyes (retina, I guess, but IANAD) from squeezing your eyes shut. You can also make it happen by pressing firmly against (or, if you’re a real masochist by striking) your eyes.
James Dickey wrote an incredibly moving poem about this phenomenon called “The Eye-Beaters.”
[sub]I can’t believe I just said something nice about James Dickey’s poetry.[/sub]
If you see stars after coughing, especially after a coughing fit, it’s probably due to vasovagal stimulation.
Coughing causes the pressure inside the chest to rise, thus squeezing the vena cavae, the major blood vessels that return blood to the heart. Reduced venous return leads to reduced cardiac output, so blood pressure drops. Raised intrathoracic pressure also causes direct stimulation of the vagal nerve, the nerve that provides inhibitory stimulation of heart rate (amongst many other tasks).
The result is a drop in adequate supply of blood to the brain, hence less oxygen and nutrient. This explains fainting and the sensation of seeing stars (as explained by an earlier post that mentioned the dip in supply to the visual cortex).
In most people the system spontaneously recovers quickly, when compensatory reflexes act to increase arterial pressure by increasing heart rate and cinstricting arteries.