Wait, that last piece of advice implies that Graf either does not believe uh, "wifely duties" should be done 3 hours before sleeping, or refuses to "stimulate" with the mouth.
That aside, it's not really that it strains the stomach. In fact it actually makes the stomach's job easier since you are going into parasympathetic mode so it can extract more calories out of the food you ate. That's why you get fat if you eat then sleep.
Keep it in your mind to not let anything pass your lips 3 hours before sleeping!Lack of sleep and stodgy stomachs will lead to obesity.Eating before going to bed places a strain on the stomach.