Why is it...?

Why is it that getting sleep after a long stint of sleep troubles makes me more tired and not less? Ever notice that? Maybe it's just me. I love sleep, but I don't always get it. I've gotten pretty good with handling the physical effects of sleep dep.

Mostly, I do ok until the fifth or sixth day of low sleep or the third day of no sleep. By ok, I mean that I function and I'm not miserable. I can work reasonably and as long as I maintain my lists, I don't tend to lose track of things.

However, I get one solid night of sleep and suddenly I'm getting sleepy in classes and forgetting to do things like ... eat.

Surely things should be easier with sleep. Right? That's gotta be the whole point.