My 4 month old son's left hand moves like he has no control over it, is that normal?

My 4 month old son's left hand moves like he has no control over it, mostly when he is laying down. He hits himself in the face with it and it just goes up and down really fast. I was wondering if that was normal. I mean he uses it to touch things and he can grab it with the other hand, but when he is laying it just starts to do that.My 4 month old son's left hand moves like he has no control over it, is that normal?
Maybe he suffers seizures.My 4 month old son's left hand moves like he has no control over it, is that normal?
If he's trying to go to sleep when he does that maybe it's his way to self soothe. Some babies bang there legs on the ground or do other things. If it isn't that then I'm sure everything is ok as long as he can use it and everything is working fine. My son sometimes moves his hand around kind of like a wave movement and it doesn't seem like he even knows its happening.
If it's just something that happens every now and then and he's not in pain then I think it's pretty normal. Newborns don't know that they have arms and legs. It sounds like your son just haven't realized that he has a left arm yet. My son was the same way when he was younger but grew out of it around 3 months. You son will grow out of it soon enough. If you are still worry then ask your doctor when you next see them.