Fuzzy Headed

I've noticed recently that I feel what I can only describe as fuzzy-headed.  I don't recall ever feeling so... numb-skulled.  I wander about at work with a myriad of things going round in my head but they go so quickly that I often forget what it was I was thinking about.  My memory seems to have become progressively worse (or I've merely become more aware of it) and my ability to concentrate on reading and writing is irritatingly short.  I also seem to have become far less eloquent than I once was.  I often forget words when I'm speaking or have to actually mentally locate the word I want.  I just feel mentally numb.

Now this could be down to a few things:

• Smoking too much weed
• Over a year of inadequate sleep
• Taking sleeping pills
• Old-effects from anti-depressants
• Poor diet and exercise
• Drinking
• Lack of significant regular intelligent pursuit and conversation

I don't think it's the weed as I don't smoke it even half as often as I used to.  I could be sleeping pills, though I haven't taken them for a while; the same for anti-depressants.  I do drink too much and I don't half as well as I used to.  I rarely get more than 6 hours sleep a night, often less, which no doubt has something to do with it.  And well, what do I do when I get home?  I don't know, I tend to sit in a mute daze a lot of the time because there's no one to talk to.  I can't read or write because I'm too anxious to do either so I watch the idiot box, which does exactly as it's called.

Any thoughts?