Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central nervous system. It quiets neural activity.
Mechanism: Binds GABA-A receptors (fast inhibition, target of benzos, alcohol, Z-drugs, propofol) and GABA-B receptors (slower, target of baclofen). Maintains the excitation/inhibition balance in the brain.
Use case: Endogenous GABA is supported by sleep, magnesium, glycine, theanine, breathwork. Compounds like progesterone (via allopregnanolone) modulate GABA-A positively.
Caveats: Oral GABA supplements don't cross the blood-brain barrier. They don't work centrally. Stick with upstream support and indirect modulators.