Hi Reepin and welcome back!
Although I am sorry to hear of this troubling issue you're experiencing currently. :/
It sounds to me like the effects of adrenaline. When we wake from a dream...or even just naturally, sometimes underlying stress or Cortisol can cause a surge like this.
It sounds like you are handling it well, with calming techniques before it can spark an attack...so that is great work on your part!
Maybe increasing your daily coping skills, especially before bed could help to keep your nights calmer w/out dealing with this symptom.
Keep us posted on your progress, as it is always good to hear from you and share in our challenges and victories!
(((Hugs))) right back atcha!
S.C.