Well, I can't say a supplement has ever left me withdrawal type symptoms other than the OTC sleep supplement Somatomax. I've been taking it every night (1/2 a scoop before bed) for close to 2 months now and it's pretty safe to say if I don't end up taking it one night my sleep really suffers. I've had sleep problems ever since battling adrenal fatigue over the last 3-4 years, my adrenals used to be so bad I would wake up in the middle of the night sweating and shaking due to extremely low cortisol and having low blood sugar. That since has stopped, however most nights I have higher cortisol levels and it keeps me up at night. Ever since taking Somatomax I average a good 7-8 hours of quality sleep and feel so rejuvenated upon waking. However since increasing my doses of l-carnitine and green tea mid-day my sleep is more disturbed now and I wake up after only 3-4 hours to piss and then fall back asleep. I went on a business trip recently where I forgot my Somatomax and that was complete hell, Benadryl was the only saving grace to get me to sleep and stay asleep. Phenibut is a key ingredient in Somatomax and Blackstone Labs Anesthetized, I wish the supplement store who sold me the Somatomax would have told me not to take this every day. I feel I will need to slowly wean off the Somatomax to recover my GABA receptors as the Phenibut is working its magic. Anyone ever have similar effects from this supplement?