This was my thought as well. The problem with candy being a superstimulus is that each time I walk past it in the kitchen I have to exercise willpower to not eat it. While I'm asleep, the reason that I remain asleep is certainly not because I'm somehow giving in to temptation. So the analogy doesn't work for me.
I do agree w/ Guzey that "sleepiness, like hunger, is normal". If I'm not feeling tired I stay up.
If anything, the same analogy applied to my personal experience would tell me that ~7 hours of sleep IS normal. For me the analogy looks like:
I only eat when I'm hungry; I eat until I'm satisfied. I'm healthy and not gaining weight.
I only sleep when I'm tired; I sleep until I'm rested. I sleep 7-8 hours on average and am happy with my energy levels.