Of course the word "sleep" in this context is referring to death. So is my baby going to die if I leave her in this nursery? And "changed" is not referring to putting on a new diaper either, in case that's what you assume also. I love this verse. It's an encouragement to so many who have lost converted relatives to the temporary physical separation called "death." This mortal body will eventually disintegrate and we will be resurrected and our souls enveloped in brand-new immortal bodies at the Second Coming (I'm a post-tribber, in case you're wondering). The subsequent verses remind us that death will be conquered and sin defeated. Wonderful words to encourage our patient continuance in the faith.
Where have you seen verses pulled out of context? It's a bad habit. I'll be advocating for a replacement verse next time I see I Corinthians 15:51 on a nursery wall. What about:
"Suffer the little children to come unto me, and forbid them not: for of such is the kingdom of God." Mark 10:14b