The phrase "chocolate coma" refers to a feeling of extreme sleepiness or heaviness that some people experience after eating too much chocolate. Full definition
For a human, a few too many Easter eggs can be seen as a bit indulgent and lead to an afternoon on the sofa in a self - inflicted chocolate coma. (fallsroadvet.com)
This was a serious case of one going into a chocolate coma the moment you have a bite! (cooking4allseasons.in)