I tried a bottle of PharmaGABA, also said to cross the BBB (that's blood-brain barrier, not the Better Business Bureau!) According to Thorne labs:

"The natural GABA in Thorne's PharmaGABA-100 is produced via a fermentation process that utilizes Lactobacillus hilgardii, the bacteria used to ferment vegetables in the preparation of the traditional Korean cabbage dish known as kimchi. Clinical studies show this natural form of GABA can increase the production of alpha-waves in the brain, creating a profound sense of physical relaxation while maintaining mental focus.* In contrast, the stress-related beta-waves in the brain are decreased.* In addition to changes in brain waves, natural PharmaGABA has been shown to produce relaxation, as evidenced by reduced pupil diameter, heart rate, and two natural markers of stress – salivary cortisol and chromogranin A.* In a head-to-head, double-blind trial of natural PharmaGABA versus synthetic GABA, synthetic GABA did not demonstrate these positive effects."

I did not notice any kind of effect.