https://www.ncbi.nlm.nih.gov/pubmed/26353411 https://selfhacked.com/blog/need-know-vitamin-c-32-science-based-health-benefits/ I stumbled across this when I recently cut my vitamin C dose in half (I'd been taking 8000 mg a day in 4 doses). I had cut this dose in half, I forget why, and I don't know if there was a connection but I noticed after maybe a week or so, I was feeling quite flat and unmotivated to do anything. Even with ME/CFS this was unusual for me. I was also having severe sleep problems due to a benzo taper, and I had found that vitamin C helped with that. Anyways, I went back on my higher dose to try to remedy my sleep, and within a day or 2 my mood and motivation picked up - still of course I lack the wherewithal to do what it is I want to do, but it's nice at least to want to do things. So I wondered if there was a connection between low vitamin C and anxiety and depression and found several hits, to my surprise. I know my dose is high but I think I need it and do well with it.