I'm a little confused by your comment - so I had been diagnosed with depression twice and once in those times I was fluent for a whole year (shitty mornings, and shitty mood so it is anecdotal but it just shows a stutterer with perennial shitty mornings won't necessarily have a worse stutter) which brings to me my next confusion, you said 'you can find lots of research on this' but then said it won't mention stuttering? So if it doesn't mention stuttering then what would I be researching related to having shitty mornings and low optimism? I'm just confused it wasn't that clear but if you can provide some of that research that'd be awesome! All the best. Also you mentioned stuttering was neurophysiological with which I don't doubt as it seems that it is linked with stress and anxiety whether that is a cause or effect. Anyways, one thing a program taught me that will always stick with me and I say before every scary situation "Fear does not equal stuttering" then I implement their methods and so far have been pretty successful so that might help a reader. I think it kinda proves that although you are fearful you can still say what you want to say fluently or atleast more fluent.