I used to tell my kids “Just pretend to sleep, trick me into thinking you are sleeping, I don’t know the difference. Just pretend, lay there with your eyes closed.”

I could tell, of course, and they did end up asleep, but I think that is like the Turing test - if you are talking to someone and it’s not a person but you can’t tell, from your perspective it’s a person. Not necessarily from the perspective of the machine, we can only know our own experience so that is the measure.