Either way, these visions were enough to push Batman to take action against Superman by building his own armor and crafting a Kryptonite spear.
Batman has always been a person naturally suspicious of the world and always on edge, but the events of Batman v Superman: Dawn of Justice pushed him to new levels of paranoia.
The dream involving the bat-creature was enough to jolt him awake in a cold sweat.
I mean, maybe Bruce Wayne could have just gone to see a sleep specialist, but trying to kill a Krytponian hero as treatment works too, I suppose.