... service accepted Phenibut CAS No.: 1078-21-3 used for reduce fatigue and improve neurological function 1. Introduce Phenibut CAS ... acid (GABA). It is used as medicine. Phenibut is used for anxiety, fear, trouble sleeping (insomnia), tension, stress, fatigue, ... depression, alcoholism, and irregular heartbeat. It is also used for improving memory, learning, and thinking. How does it work? Phenibut is ...