Help I'm sitting and I can't lay down!!!

So our little Jack has mastered getting into the sitting position.

Sounds great, right? Well it is, except now when he is so tired

and just wants to go to sleep we lay him in his bed and 2 seconds

later he finds himself sitting up! The first few times he did it he thought

he was pretty cute, but now that he is totally worn out he can't seem

to figure out how to stop sitting and lay down!!!!