When I first got my studs, I took them out every night, and put them back in the box. Then I went on a trip and didn't dare take them out at night and found I could sleep in just fine. So I sleep in mine. I take them out every two to three weeks to clean them. they are H & A so they sparkle a lot whether dirty or clean.
I don't sleep in my rings, its uncomfortable because my fingers swell in the night--but my ears don't swell and my earrings are very comfortable, though they definitely aren't small.
I heard to be careful with screw backs--the threads wear out and people don't know and then lose them. Mine are la poussette--i heard that's the safest.