Trading is great advice and I have a bit to add. You have to practice giving the valued item RIGHT BACK. Loki used to be like Layla and I worked with him for months (and still do just for fun) and he is MUCH better now. I did the trade with a higher value item and I used the command "drop it" and he also knows "leave it" but that is for things he does not yet have, like a sandwich on the table, but same concept!
Anyway, when he is chewing on something I go over and sit by him and pet him and say "Drop it!" as happy as I can - he will give me his stick and I look at it, say "Thank you!" and give it right back and continue to pet him while he resumes chewing. That way he is used to someone invading his space while he chews and if he knows he is going to get the item right back he doesn't mind giving it to me. Do this a lot so that the one time you do take it away (like at bed time) it's not the only thing they remember. Just make it a game. Give them the stick. Ask them to drop it. Ask for a sit. Hand it back and sit there and pet them for a minute. Then repeat! Loki gets bored after a few times and I swear he rolls his eyes at me, but he does what I ask.
I really need to do this with Sam too. She doesn't snap so I haven't had the need to teach her but I really should. It's funny how the dog who was worse when he was a puppy is trained better than the "good" one out of necessity. We think Sammy is smart but she relies on her cuteness most of the time instead of her brain LOL