13 Japanese volunteers got: 100 mg of GABA or 200 mg L-theanine,

13 Japanese volunteers got
100 mg of GABA or 200 mg L-theanine,
Then got their brain waves tested on EEG.

alpha waves (less than 8–13 Hz) increased by GABA more than L-Theanine.

beta (more than 13 Hz) decreased more by GABA than L-theanine.

Both compounds shown to be effective as inhibitory factors, and can be used to calm the nervous system, slow down brain waves, improve sleep and decrease anxiety.