Hi Jack's Mom.
I am always interested in hearing about sleep behavior because of my experiences.
In my case, I have been on Keppra for quite some time, but I stopped when I was in my early 20's. About that time I started moving a lot in my sleep, punching and kicking, talking more than usual. My wife got used to it.
This carried on even after I started taking my medicine (because of a T/C). As the behavior carried on, my neurologist diagnosed it as RBD (Rem Behavior Sleep Disorder). My doctor prescribed Valium which controlled it to an extent.
Later I had an at home video EEG. The data all read normal, but after observing my behavior, my neurologist noted the specific behavior as not being normal dream behavior and likely a partial of some sort even though there was no sign of it on the EEG. I was prescribed Vimpat and I sleep like a baby.
It is something definitely worthy of taking to the doctor about. Things to look for (and probably record for the doctor) would be repetitive movement, such as kicks, punches, awkward contorting, etc. Also the gibberish is something I would want to talk to a doctor about. During partials, when awake, I would speak gibberish. My behavior became odd when "asleep". I would throw things and not know it, or slap my wife. Yes, that happened.
One thing I forgot to mention, according to the EEG, I was awake.
In a nutshell, get him to the doc.