Can Juvederm spread when put in nasolabial folds if you're a stomach sleeper?

I haven't seen filler move to the extent that you are describing. BUT- I would touch base with your MD to let him know your concerns. Juvederm can be reversed but you may not need that- a clinical examination is important for you. 

Don't worry about sleeping on your stomach as you cannot spread the filler out of the nasolabial fold.
I do wonder weather you have lost some fat ( volume ) in your cheek and as a consequence the skin starts to hang and then give the impression that the fat just beside the nasolabial fold is fuller.
If for some reason some of the filler hs been placed outside of the nasolabial fold then yes hyaluronidase can flatten the area by just using a small amount. Your doctor will be able assess the area for you and explain what is happening .
I hope this helps .

Thank you for your question.  In my experience, it takes sustained, firm massage to move or displace Juvederm or other hyaluronic acid fillers.  The light pressure on your face from sleeping on your stomach is unlikely to cause your Juvederm to spread.  Although it does spread slightly from injection points, hyaluronidase certainly can be used in specific areas to dissolve unwanted filler.  Revising filler is a fairly complex procedure - I would recommend seeing an experienced cosmetic dermatologist or plastic surgeon.  Best of luck!