My baby grunting and making all kinds of noise when sleeping. Is your?

My LO is grunting, sucking air in so it sounds like he can't breath, giggling and making all kinds of noises whilr he sleeps that have me on high alert. Nothing ever seems to be wrong, but it freaks me out and I have trouble sleeping because I am listening on high alert! What is going on? What causes this? Anyone else have this experience?