Just got to experience what it feels like to have no sleep at all in 48 hours or so. It is not fatigue that one feels, but extreme irritation (of the mind) and intense frustration. It is as though you become pissed off with nothing. It definitely feels as though there is no direct link between this and the lack of sleep but I guess the brain is failing to work well. For me, my brain started confusing emotions and rationality, intellect and lame-ness. Eventually, I was feeling pretty lost until I got to sleep, much later.
Energy Nerd | Circular Economist