It seems like it should hurt but it doesn’t. It feels soooo good. Why?
Ever had the seven year itch?
I think it temporarily numbs the area.
Counter-irritation to essentially give the brain something else to think about. That’s the reason why, when you whack your leg into the coffee table, your first reaction (after swearing) is to rub the area.
Here’s an Interesting Article on the Subject
I think this is a big part of it:
The itch sensation is technically known as pruritus, and it’s thought to have evolved as a way to protect skin - our largest organ - from parasites and build-up of dead cells.
I do, however, think that the “scratching her way to her brain” comment is bullshit.
For the same reason that poop stinks, sex is pleasurable, acrophobia, we’re afraid of snakes, and fingernails on a chalkboard gives us a chill: evolution. There was something in our past that mad it advantageous to scratch. Those that didn’t scratch suffered the consequences, perhaps death.
I wanted to believe it couldn’t be true, but…
Intractable postherpetic itch and cutaneous deafferentation after facial shingles
The factual question here is, “What is advantageous about scratching an itch?”
Back a few hundred years ago, the itch was likely to be caused by parasites (fleas, lice, etc.) on your skin. Scratching dislodged them , preventing them from sucking your blood – good for your health.
So the humans who scratched an itch had slightly better health, so reproduced more, so over a long time evolution reinforced the tendency to scratch itches.
But sometimes it’s bad to scratch an itch caused by parasites too much because of the danger of infection (especially in former times with less hygienic standards). And I think it’s also bad to scratch an itch caused by a tick bite when the tick is still attached to the skin because of the possibility of snapping off the body and leaving the head in (another infection risk).
I suspect the remove parasites is a good hypothesis. But why do we itch anyway? There is a place on my back that always itches, with no parasite to explain it. Left side only. Oliver Sacks said that one of the worst parts of dying from ALS was not being able to scratch.
I came across this reddit thread discussing this very topic:
ExplainLikeI’mFive: why does scratching eczema (or similarly irritated skin) feel so good and provides relief in that moment, when in reality it worsens the skin condition?