it's definitely a very fine line - and sometimes so hard to tell, isn't it?!
with ds, i found that if i went into him and he got louder & angrier, i never should have gone in, cause it wasn't his "i need you" cry. it took me a long time to learn how to distinguish that cry, but once i did it became much easier for me to respond to him.
especially around the 4-6 month range, he made lots of noise in his sleep. most of it was normal resettling, and once i learned to ignore that, it helped him sleep better.
also, fwiw, at night i only ever got out of bed if the cry escalated. then i ran fast! :lol: