Violent & Angry upon awakening...

So for the past few weeks at least, when my husband is waking up in the morning he can be very mean & agressive taward our 2 year old son (spanking, screaming, hitting back ((not too hard))

He typically works until 1am, and he's a type 1 diabetic so he deals with his sugar until it's stable enough that he feels comfortable to go to sleep and usually ends up being around 4am.

So in the mornings, around 8-10am when our son wakes up he's usually kicking/hitting/being rough in bed.. because he's 2.

My husband, asleep mostly, gets really angry with him and is way too aggressive sometimes.

when he's fully awake, he realizes what he's done and usually apologizes and feels bad. like he didn't know he was being so mean. He's fully aware this is becoming a problem and neither of us know what to do. He's incredibly hard to actually wake up.

he sleep talks pretty bad sometimes and even gets up/has conversation in his sleep and doesn't remember.

can anyone else relate? Ideas to wake him up easier without him freaking out? or just don't try to wake him?