i see some threads about GHB
but i'm questioning how lethal is it really... i dont want to wake up more wrecked
I can't give you an answer, but let me give you my approach to suicide methods: euthanasia societies founded by doctor and scientists, that know best if a method is reliable and reasonably painless, mention suitable methods in their publications. I would just consider those, that are mentioned there. I think GHB is a downer, which would probably stop your breathing in a high enough dose. If it's reliable and painless enough i can't tell.
Always keep in mind: People here aren't experts, at least most of them aren't and although non-experts could refer to scientific informations, it takes a lot of knowledge to know what to make out of them.