Falling asleep while eating

I guess it is possible because Jack did it the other day!  We were taking a drive to one of the many lakes out here.  It was close to nap time and lunch time so we pulled out our PB and J sandwiches hoping we could get Jack to eat lunch before he fell asleep.  He actually did eat most of his sandwich, with his eyes closed.  I had to talk to him and nudge him several times to get him to finish chewing!  He must of just needed a little food fuel because after his sandwich he was awake to eat the rest of his lunch and not too long after that he was dancing around at the lake!