While you're laying, here's some things to try.
Experiment with isochronic tones/binaural beats. Continue with your reality checks. Try and envision yourself in your comfort zone, whether it be in a white room, your friends house, the beach, or whatever the case may be. Make this vision very specific and detailed. Example, at this beach, envision the tide, the sun, seashells, birds, etc.
Other than that, what helped me a lot is Om Meditation, and reality checks all throughout the day.
Something that might help with remembering to reality check, is to mark something on your hand with a pen. It can be a line, a dot, the letters "rc," whatever will trigger it in your mind will help you tons.