Disciplining young kids

So this is brand new to me and I want to know what you all think.

My two older kids (4, girl and 2, boy) act like they hate eachother and it’s frustrating.

We had to put them in the same room recently and to save space we got a bunkbed. My oldest is a very bad sleeper and every night she wakes up at least once. Yesterday, my son wanted her to come down to sleep with him on the bottom bunk, which they do sometimes. He tried to wake her up and went a few steps on the stairs of the bunkbed and she pushed him off and he fell to the ground. I’m wondering what to do in these situations because we do want to discipline them but how to do that in the middle of the night? We just told her to go back to bed and we put our son in a pack and play in their little sister’s room (and we’ll try it out like that for a while)

Now this morning my oldest was still in a cranky mood and I’m not sure what happened because we didn’t see it even if we were in the same room but she hit her brother in the face and he had a bloody nose.

She has a lot of anger inside her and we are seeing someone to address that but I want to know in the moment, what’s an acceptable punishment for violence?

We usually do a warning, then time out for 5 minutes (for her) and 3 minutes for her brother for things like not listening, arguing, but should we do something else for things like that?

They’re still young and I’m not sure if there’s another method we could try?

I’ve tried to talk to her to understand what’s going on but again, she’s just 4 and while I know she understands what she does and what the consequences are, I’m not sure she understands why she does it.

Her brother will usually try to defend himself as much as he can but most of the times just cry as soon as she touches him. On rare occasions he’ll hit her back but she just hits him harder.

ALSO. This seems to be only happening at home. No complaint from the daycare at all, both of them.

Please can I get some input on this, any similar stories, any miracle remedies!