Never took phenibut. I use GABA and Melatonin.
Start w/ 2g GABA empty stomach. You cant take it and keep active. take it and lay down to bed, like lights off or whatever you do. I take 3-4g GABA and 1.5mg Melatonin within 10-15 min i feel my GABA rush and begin to feel weakend/ very very relaxed muscles and drift off.
Don't freak out w/ a GABA rsu, breathing may get heavy and a tingly feeling all over. It is not bad.