I’ve heard all the medical reasons of why you itch. The histamine reactions in your body are sent and make things itch (I dunno if this is true for just basic “itch-spots” that show up or not). But why does your body believe that stratching the itchy spot will relieve it? And since it obviously does, why does the spot stop itching? Does the histamine reaction stop because you scratch the skin?
WAG: For small itches, the act of scratching floods out the sensation of the itch and breaks a feedback loop. For larger itches like a mozzie bite, the relief from the tactile ‘flood’ is temporary, until the histamine sensation overrides the vanishing tactile ‘aftertouch’*.
The act would be one of your bodies defenses against parasites or small foreign bodies.
Bet you have an itchy spot that is itchy right now. Scratch.
*word i just made up. Akin to afterimage.
I’ve also heard the theory that the act of scratching an itch can scratch the ends off some of the sense receptors on the skin, thus stopping the itch.
You’d need to scratch yourself bloody to do that I think.
I concur with the overload idea. The nerves conveying the itch temporarily quit sending when they get a flood of other sensations. You can get the same effect by lightly smacking the itchy area. When you relieve the itch without scratching, you don’t damage the skin.
The explanations above sound very similar to the pain gate control theory.