This is very sad to see and I wish Dianna and her family the very best for her recovery. I'm into year three of long COVID (ME/CFS) and was fortunate to not reach this level of severity, and to have improved slowly with time to mostly housebound rather than bedbound, but it is a remarkable disease.
The name does it little justice, and fatigue - while certainly pathological and disabling - is not the primary feature. The disease appears unique in terms of an abnormal response to exertion. This has been characterised via two-day cardiopulmonary exercise testing. Healthy controls and even those with other severely limiting diseases will show improvement on day 2, but ME/CFS uniquely shows a reduction on the second day.
Other key features are orthostatic intolerance with demonstration of reduction in cerebral blood flow in the majority on sitting/standing. Neurological symptoms including extreme sensitivity to light and sound explain her blindfold and ear protectors. Many have fluctuating cognitive slowing ("brain fog").
New insights into the metabolic derangements are being gained. Recently[1] evaluation of urine metabolomics demonstrated that healthy sedentary controls excrete many metabolites at 4 and 24 hours following an exercise challenge, while ME/CFS patients do not.
Apart from the devastating effects on patients and the economic impacts of losing so many from the workforce[2], I believe that understanding the immune and metabolic derangements underlying this condition will lead to major insights across many health domains.
[1] https://www.mdpi.com/1422-0067/24/4/3685
[2] https://www.nature.com/articles/s41579-022-00846-2