Since I am married to a man who GRINDS his teeth in the most horrific manner
during sleep, I would suggest that maybe the baby is doing a similar grinding
of his teeth during sleep.  Perhaps a massage before bedtime, with focus on
the face and head.  Reduce daytime stresses as much as possible.  Maybe even
the mother's own caffeine intake can be affecting her nursling.  If mom is
not separated from baby during the day, offer the breast more often if
possible.  If the problem is *mostly* during nighttime, then some (difficult,
I know) steps to night weaning may need to be taken to preserve the *rest* of
their breastfeeding relationship.

Lisa Jones, LLLL in Wellington South Florida