I"m like Nick. My (well planned) training sessions usually go for from 90 minutes to 2 hours. Working with usually 4-5 lifts. I find that if i have a high GI drink (for example a slightly diluted powerade) towards the half way mark, i remain productive & able to keep going forward.
Like Nick, I'm never sick. Like, never. I eat great. I sleep like a log. Your body doesn't know time, it just knows when you've stopped the stimulation.