Neuropsychopharmacological/Neurosteroids/Neuroactive steroids and everything about them is am interesting subject. One I have just taken a big interest in in the last week or to. Its not somthing I would even come close to acting like a expert in but I can tell you this. I will be researching it heavily and learning more every day.
That being said what the hell lets talk about this shit lol. Lets start with GABA as a sleep aid. To my knowledge even in high doses synthetic GABA doesn't cross the blood brain barrier that well. So has little to know effect on sleep or neurotransmitters.