why do I giggle in my sleep?

My husband says that I always giggle in my sleep.
Just a few nights ago I did it again. I had a little giggle, so kevin asked what I was laughing at, knowing it was my sleep giggle. I replied in a very clear, not sleepy,and excited voice and said "I got most of it!"

Well Kevin slept talk a bit the other night too; well I would call it slept mumbled. He woke me up in he middle of the night mumbling, so I woke myself up so I could try and talk to him. I asked him what he was saying, and he just kept pointing to our wall and saying "mwahdihalkddkfhwaaa." He did this for me three times before I got bored of talking to him so I fell back asleep.

So I keep thinking, what does this mean? Maybe that my brain works better than his when it sleeps? My brain is more developed than his is? Who knows...