@taylan My impression is that the skin on the shins tends to dry out easily in general for some reason, and dry skin is very often itchy skin. I might have no dry skin issues anywhere else, but my shins might still be slightly flaking.
You could try applying some moisturiser before bed and see if it helps after a while. Loads of options out there, from heavy thick ones, to thin watery ones that absorb quickly.
When I lived in Finland, something in that particular town's water dried my skin like mad, and I spent a lot of (unscented) lotion just to keep the itching down.