Maybe do a cutback on those sugary foods, try more fruits which in fact have sugar in them but are not so concentrated and natural ..It may also be coincidence ,is this during the day ,is she at day care ?
Well she eats good she plays and sleeps at night very well. But when she eats candy chocolates puddings cookies or even cereal with sugar she falls asleep instantly
What kind of sugary foods do you mean a desert or a snack ,, it very often hypes them up ..Maybe she is just tired , what does her daily routine consist of does she have a good appetite ,and sleep well at night .?