[tdq]

Just my thoughts - while my conditions is way less "serious" than other posters, it still affects me from time to time. I have - and I only recently figured this out - "Depersonalization-derealization disorder", where you feel detached from reality . This took hold in my late teens-early twenties - I'm pretty sure it was triggered from over indulging in certain substances...It lasted for several years and was quite debilitating but gradually grew less severe over time. It still rises occasionally but I usually manage to "forget" it's there.
One thing that really helped was finding out that others had the same issues and I wasn't going crazy. It really was the beginning of the healing process for me. So, sharing is good, and thank you everyone for being open.
As for how it effects my guitar playing - I don't know but I can get lost in playing (my wife says I get a guitar face where I disappear) and ironically it can help when playing in front of others, where they recede from reality a bit and I'm just in my own in my head - although it's not quite extreme as that sounds!!
I don't know what I'd do without guitar. Probably be playing banjo.