Hi! I used to work a place where I felt like sleeping right after lunch, in that firm there was "free" lunch. The lunch was quite nice and "heavy". That was infact my first place of work right after studies. Now I have worked many places and never felt this urge to sleep right after lunch. I have come to the conclusion that the reason why I felt like this after lunch was because of the food that was served at that firm.

You shouldn't do anything at all. I see it as quite normal thing to do. I won't hurt the firm you are working in at all.