I did the ironing and found the issue I was having and fixed it.
I'm technical and that got in the way. I never understood how I arrived at deep meditation except that I would just fall into it. I had the technique down to the letter. But when I applied critical thinking at how I actually arrived. It all went out the window.
I arrived at deep meditation shortly after I started daily meditation practice. I reason why is because I expected that meditation practice would lead to something pleasant, and an altered state of consciousness.
It is also possible that those who arrive at deep meditation have exceptional IQs, as I do, and it seems that you do, and it seems most of the people on this forum seem to.
The feelings of anxiousness is the immutable current state moving to the mutable.
I noticed that as I meditated deeply that I would become aware of the mental state of others. I happened to find it easier to meditate deeply when in the wilderness, so I went on hikes nearly every day, as everywhere in Tucson is only about 20 minutes from a hiking trail. I also spent at least 2 weeks camping in the wilderness every year, as well as I attended at least one 10-day meditation retreat each year. So, I developed skill with deep meditation, and self-awareness.
There were times when I felt anxious. When I examined myself I could not see a reason for the anxiety and determined that I was becoming aware of others around me who are anxious. And, 13 years ago when I increased my meditation practice I headed off into the wilderness where I would not feel the anxiety of others. So, since you are meditating deeply, then possibly the anxiety that you feel is the anxiety that other around you feel.
A few answers would be helpful from your own experience. I'm sure you have written about this?
Why do we get absorbed in deep meditation?
It is a natural state that some people who are more intelligent than others discover on their own when they take up a contemplative life.
Do we have these states when we sleep but unaware that its taking place?
We can. I have, but most people do not, because they do not lead a contemplative life.
Why does one feel bliss?
It is simply part of the experience of deep meditation. Also, if it was not blissful, then it would not be compelling enough to pursue deep meditation, as well as put up with the strange charisms, as well as the spiritual crises that are part and parcel of an interior life that goes to depth.