It may or may not be true that neurotransmitters are going to hold an individual back, but I agree with Howetzer that a lucid dream can't be worth getting a chemical addiction. Surely?

Besides, might there not be the possibility of biofeedback ? I'm unsure if it extends into the realm of altering your neural chemistry, but it can at least alter the frequency and state of mind at will.

Addictive chemicals seem like an incredibly dangerous way to go.