If an occlusal appliance is well made, you won't be able to grind your teeth , either consciously or subconsciously. All appliances may look similar, but there is huge difference , which can only be ascertained by experienced tmj specialist or occlusionist.
Seeing a competent tmj specialist is advised.
Oh, I can imagine what your experiencing. Waking up with that pain. That uncomfortable Night guard. But, lately I try ordering a Custom fitted night guard off the internet. and let me tell you what a relief it has been. nothing compart to the night guard I bought from the dentist and much cheaper. Only $79. The link is posted below. I highly recommend them from personal experience.
http://oralresource.com/custom-night-guard.htm
don't wait. You don't have to live with the pain.
I too was grinding horrendously and especially as I was dozing off when I was a passenger in a car ( while still conscious) . It was while I was a passenger in a car one day that I tilted my head back and noticed immediately that the grinding stopped, just like that. That night, I slept on my back for the first time ever and wouldn't you know it, no more grinding in bed either.
My dentist never told me that laying on your back normally resolves it. If you type bruxism cure in the google search engine, you'll find many people recommending sleeping on your back as a way to stop it altogether or significantly reducing it.
It really does work wonders for me and hope it does for you too. Just don't get sucked in by people making money from your suffering such as getrichquick schemers who prey on the vulnerable with self-help techniques that is all common knowledge by a quick google search.