Not sleepy! Not sleeping!

Image picked from WWW

I was unable to understand what George Carlin meant when he said this but now I think I get it.  

Anyway, this hasn't anything to do with my title except for the fact that it sort of ties in with what crossed my mind recently.

I was thinking about kids when you want them to go to bed and they always say, "not sleepy".  But if you keep them in bed, they eventually fall asleep within minutes.

And older people, you catch them with their eyes closed and then when they wake up, they say, "Nope, not sleeping".  

So the young don't believe they are ever sleepy (at bedtime) and the old don't believe that they were sleeping (or napping on the chair). 

It all seems funny somehow.