You wrote you're retired from work now & "feel very far from being forced to live these anxiety levels." I haven't been actively employed for 20 years now. However I "ran on my nerves", so to speak, throughout my childhood as well as throughout my working years. Since then, similarly to you it sounds like, I still experience high levels of anxiety.

My body feels as though it's churning 24 / 7 even though I have virtually nothing to be anxious about. So I've come to the conclusion my body was wracked with anxiety for so many years it simply no longer knows how to function any other way regardless of whether there is anything to feel anxious about or not. Perhaps this is the way it is for you too?

Here are links to 2 articles, from PC's archives, on the subject of nightmares just in case you're not already familiar with them:

More Than a Dream: The Science Behind Nightmares | Change Your Mind, Change Your Life

How to Eliminate Recurring Nightmares