I do not sleep walk I actally have Narcolepecy,and I use to bite my nails as a kid but never in my sleep and I stop bitting my nails in my twentys.
you bite your nails in your sleep? Wow .....Can only think this is from stress.... (like some people grind there teeth when they sleep) ...... Are you prone to sleep walking at all ?
STRESS or actually a lack of a nutrient...I would put gloves on to you figure out whats causing the isssue.