Re: 3yo screaming bloody murder after nap?
Mine wakes up screaming/crying sometimes. Unfortunately, when it happens, it's usually when we have to go somewhere, so I try to give her time to calm down, but there's not much time available before I have to basically force her into clothes/socks/whatever might be necessary and then shove her in the car kicking and screaming.
However, I will say, that once we start driving, she calms down really quickly. I still have yet to figure out what will indicate waking up crying vs waking up happy, except that most times she wakes up crying, it's when I have had to wake her up.