Training Mask before you go to bed!!! There won't be much sleep involved! And stray thoughts will be bouncing off the inside of your skull like Ricochet Rabbit! Prescription for insomnia right there. Trust me. Here there be monsters. Definitely not one of my smarter moves and it won't be repeated in the future.
(But the mask is an interesting tool, if you use it correctly (and during the proper time!))