Depressed . . . or just tired?

I have found, of late, that it is absolutely impossible for me to differentiate depression from physical lack of sleep. Sometimes I'll get up at what seems like an early-but-not-too-early hour, having gone to bed a little earlier the night before, and I'll sit at my desk, and I will not have the faintest desire to do anything. Anything I think of to do -- work, write, read, balance the checkbook -- seem equally gray and lifeless. I might spend a few minutes in that state, thinking that this is it, I've finally hit the mid-life crisis and life will be forever joyless. Then I remember, and I go back to bed for an hour or so, and when I get it up it's a different picture.

David Wilcox had a song about this subject: "It's physiological, in a logical disguise -- you're just down inside yourself." I suppose the converse is true -- those times when life seems good and all is well, it might just be the coffee talking.