Some times it happens to me. I can start doing something in the morning, then by noon I get hungry, but then I think "Hmm, what if I were to tinker a bit with this aspect..." and then forgot I was hungry. Then later I'm usually puzzled why it's gotten so dark all of the sudden, and I look at the clock, and it's midnight, and I realized I spent all day working on my project, forgetting to eat and do stuff I'm supposed to have gotten done.
Like today, I spent 10 hours working on a ternary virtual 6502-clone (if you pardon the technicalities).
Do you ever get carried away with stuff you're doing? Completely loosing track of time, just spending hours upon hours working on some project?