Biting Nails

Does anyone else have a nail biter? My son chews on his fingers and bites his nails a LOT. He also chews on his big toenails (especially while he’s fighting going to sleep). He has hangnails and makes his nails bleed sometimes. I have no idea what to do! We of course tell him to stop but you can tell he doesn’t even realize he’s doing it at this point. He just does it absent mindedly. I figured he’d stop when he hurt himself but it hasn’t slowed him down.

Anybody else have this issue?