[eMSF]

I can't believe physical exhaustion is not at least as important a part in this. Personally, I skip a night's sleep every now and then to readjust my sleeping patterns, and I've never experienced anything strange after something like 32-36 hours without sleep (but note: no significant physical exertion involved).

It doesn't even feel that bad once you get past the slump in the 20-24 h region.

[circlingthesun]

It might be. I ran 30h race earlier this year and had no hallucinations. I've not done _exhaustive_ research on this, I'm just recalling some undergrad neuropsychology. It could also be the environment. I suspect it's a lot less likely that you'll be seeing stuff that isn't there when you are in a familiar environment as opposed to running alone in the bush.