I don't know about "normal" but I have those a few times a week. I will wake up sometimes in a panic/anxiety attack. Sometimes things will cause them, most of the time it's nothing. They just show up! Very hard to leave the house when my stress is higher, like when I am out and about that makes it easier to get them. Whether there is a specific catalyst or not.
_________________
Your Aspie score: 180 of 200
Your neurotypical (non-autistic) score: 27 of 200
Autism-Spectrum Quotient is 48
AS, OCD, ADHD - Diagnosed
PTSD - Undiagnosed
<"May the Gods have mercy on you for I shall show none...">