This is an interesting thread as it goes in the direction of the conclusion I had reached myself from my own experience.
I started peri with very distressing symptoms, paraesthesia, terrible tinnitus, lightheadness and diziness, nausea, vision in one eye going blury, low heart rate and blood pressure and overall feeling very hyper physically with thoughts bouncing in my head all the time and seeming unable to relax no matter what I did to do so.
Once it was identify that it was nothing sinister and due to the peri, I was advised to go on HRT. Sadly, it seemed to have the exact opposite effect with the parasthesia and ligheadness. It was worse soon after I stopped progesterone and then noticed the same trend when I had previously started my periods. I stopped hrt and started to feel better but the parasthesia, tinnitus, fuzy vision would still hit me at time, and finally realised that it coincided with me getting vaginal discharge indicating oestrogen (the egg white looking discharge).
I am convinced that what made peri horrible for he was oestrogen surges. It is also interesting that I get very few hot flushes.
I'm now officially menopausal (12 months no period) and feel much better already. Parasthesia is now rare and tinnitus still there but not as bad. Only the sleeping issue remains but I've now find treatment that works.
I did suffer from very dry mouth during the hrt treatment but was also taking sleeping pills thrm so put it down to that, but maybe it was the progesterone indeed.