Oh, then you're right. Maybe the carbs are making the blood sugar rise too quickly and drop quickly, making you feel very tired. Being very tired might make you feel dizzy, like you want to lie down and go to sleep. Two years ago in the fall when it was getting cold here, I'd eat a bowl of oatmeal for lunch with maple syrup (This is before I was "pre-diabtic".) and half an hour later I'd want to take a nap. Now, I realize it was that same reaction. Since I'm also trying to control this with no meds, I can't do that anymore. So, trying cutting out the toast and jam. Good luck!
Lanie