What causes the sensation of 'pins and needles' when a limb falls asleep?

When your limb goes to sleep and feels like it’s full of pins and needles, it's like a crowd suddenly getting up from their seats in a quiet room, they knock things over and make noise.

Imagine you're sitting in a big, cozy chair, and someone wraps a blanket tightly around your legs. After a while, the blanket feels too tight, and you can't move your toes or fingers very well. That’s what happens to your limb when it falls asleep, nerves get squeezed by pressure, like being wrapped in a tight hug.

Once the pressure is gone, like when you finally stand up, all those nerves that were being hugged want to shout, “Hey! We're back!” So they send signals really fast to your brain, making it feel like there are tiny needles poking you or pins pricking you. That’s why it feels so ticklish and weird when your limb wakes up again, it's just nerves saying, “Hello, I'm here!”