Coding while sick is like trying to walk through fairy-floss
I once tried to explain to my aunt (a respected Dietitian) about how you need your whole brain firing on overdrive to write truly awesome code... it was difficult to explain clearly and I didn't pull it off successfully. Apparently I left her with the feeling of "and you don't think I use my brain in my work?" which was *so* not the point I was trying to make.
In my experience, most jobs (ie non knowledge-work jobs) have an element of drudgery. Tasks that you can do with only half your brain involved. You might not be able to do them while sitting in front of the tv - or while chatting with a friend... but you can do them when you're feeling less than 100%.
Coding isn't like that. Neither are things like mathematics, theoretical physics and creative writing.
At least 95% of the tasks you do require full attention. It's not like you suddenly forget how to code (or write, or whatever), it's just that if you do that work when you're not "all there"... it'll be far more buggy and inelegant. You might be able to salvage most of it, maybe with only a bit of re-writing, but if you're seriously out of it, you'll have to re-write so much of it that you might as well write it from scratch... ie you'd be better off having not written it at all.
The last week and a half has been like that for me. I've been trying to see through a near-impenetrable fug of virus-induced head-cold.
I've watched a lot of television. I've made significant in-roads into my post-easter chocolate collection. I even began a new knitting project... but I haven't coded much.
I even had trouble concentrating enough to get through my email. When you find yourself blankly staring at the screen, and realise that you've been sitting there, doped out for ten minutes doing nothing... you know there's no point firing up the text-editor.
Still, the fog has begun to clear over the last few days, so I'm slowly picking up where I left off. Which is lucky as I'm helping a friend out - he's sub-contracted a few basic rails tasks to me on his current project. Hopefully I'll be back in full-gear next week as I have a contract-interview and a talk on Rails for my local LUG.