Yes gphx, the the key is that the exhaustion and depression are PART a Sjogren's syndrome.
You are depressed because like the dryness, your system caused to be depressed by the condition.
It is a key difference.
The depression comes directly from having Sjogren's.
You aren't depressed about being tired and miserable (tho Lord knows you should be!)).
The Sjogren's also has depression as a co-condition, physical in nature (probably chemical imbalances).
You aren't exhausted by the pain and misery (tho' Lord knows you should be).
The exhaustion is a co-condition, physical, again caused by the nature of the auto immune disease.
That is why they can hit so violently, out of the blue.
You haven't changed anything or felt different, your life seems the same, and BAM you are depressed/exhausted beyond belief.
I'll do some research to find the sources for my numbers, as I don't remember where I got them.
I'll keep you posted!