I am recovering some physical abilities but recovering cognitive energy is very slow for me. I get less PEM from a light or moderate physical activity than from even a small amount of mental effort. When brain fog lets up, I've been able to do some quite computationally intense work, but when it is in effect, even navigating to the files I work on gives me a headache and causes my eyes to blur out. I enjoy my work, so it isn't boredom or lack of motivation. I would love to be continually learning and expanding my mind. I think lowering of consciousness or awareness is a good description. I used to meditate with exercise and have fairly intense experiences. Now my mind often has pleasant experiences at rest but feels rather dulled. Keeping the thread of creative tasks is also quite challenging, similar to technical tasks. I can really see that mental activities use a huge amount of resources. Orthostatic intolerance and physical symptoms are still very much there for me, but I think the PEM from cognitive effort and the lowering of awareness are most severe. Also the descriptions here of mental PEM are good. A nearly headache and physical weakness, that becomes a very painful headache extending into the body. Mental PEM really hurts!!!