GABA and L-dopa can help in maximizing natural endogenous production of GH at night...that said it will not generate supraphysical levels. Lets say that you go to bed now and usually release only 65% of your max GH output possible...they might help reach deeper sleep and help your body release 75% (just an example , don't get anal about the numbers) , but the number will never be greater than your 100% possible...