Have you heard that when sleeping infants smile it's just gas? What do you think causes it?

Lack of control over their facial muscles at that age.

Have you heard the gas ripping through a baby’s system? I’d grimace, too.

Maybe they’re dreaming about passing gas.

@syz I am not speaking of a grimace. But many times I witnessed my own infants passing gas and they never smiled. Or, you might have been simply attempting to make a joke.

I’m with @CWOTUS. My wife says I smile while I’m a sleep.

If true, it makes me smile.

I’m pretty sure that is true for wives. Babies, not sure about.

Who cares about babies smiling in their sleep? Can you ever forget the first time you came into the room and your baby greeted you with a big grin? I can’t.

With my little guy, sometimes it looked like muscle spasms/uncoordinated movements and sometimes it looked very peaceful and genuine.

Of course it’s impossible to know. I liked to think that my grandmother, who died before he was born, was kissing him in his sleep.