Well, to McJob and Dannu, while health concerns are very appreciated, I don't think we can realistically act like anything I do is healthy. If I was concerned about my health I wouldn't be such a disgustingly negligent human. The most I see on a long-term scale is that I might be a little disoriented for the next day or two, which seems fine. The effects you're listing are for chronic sleep deprivation, so I would have to be getting little to no sleep on a regular basis for that to kick in.
I naturally assumed it would get harder, but reading some testimonies, I think it gets a little easier to stay awake after the 24+ hour mark, but comes back hard past 36+ or so. Which is why I'm gonna try to avoid caffeine as long as I can. I worry if I start on it, I'll be over it by the time it really gets difficult.