I actually asked my Biology teacher (Who studied Neurology for about 12 years) about this and she said yes, exsessive Lucid dreaming IS bad for you. Your body only rests if if can get to the Deeper states of sleep which it is not able to do in Lucid Dreaming. She said without getting to this nessisary state you will first become stressed and then eventually psycocotic. So in conclusion I would say yes.
Although please note - I don't know how much she actually knows about Lucid dreaming and her personal views (I think she's against it) may have colored her opinion.
Hope i helped! =)