Brain activity during severe recurring nightmares?

Lately, (in the past 3 years) I sometimes start thrashing around in my bed in a complete panic, I flap around trying to escape something until I m standing in the middle of my room. Usually the process of getting out of bed wakes me up and then my heart is beating so fast I feel light headed and my hands and legs shake and I remember feeling extremely terrified but I have NO memory of what the dream was. It's not night terrors because I immediately realize that everything is normal and the feeling of terror fades away until I calm down. I also don't think it's panic attacks because I'm pretty sure it's caused by a dream and trying to calm myself down doesn't make it worse like they say it does during real panic attacks. I also can't think of a trauma or something that would cause it. What's going on with my brain? Do I have a hyperactive amygdala or something when I sleep? I keep waking up terrified, what's going on with my brain? Oops, ignore the update, I thought it would let me rephrase/replace my question headline