I don't just mean feeling a little slow. I am physically sick to the point of being unable to eat food, having a headache (not every time) and not being able to process information (e.g. reading an email 2-3 times and still not comprehending it fully).
Is this a unique reaction?
So, you are saying that when you don't get enough sleep, you feel fine most of the day, except for the first 2-3 hours after waking up? This is pretty weird and I don't have a good explanation for you.
On a day when I don't get enough sleep, it takes several hours, negating whatever "time savings" there are from forgoing sleep.
On a whole, I feel like there is another side of this coin which is that being hungry might not be bad for you, but if you're hungry enough it can be very unpleasant.