I've used 300 mg caffeine daily for a couple months, so I've built a steady tolerance to it. I take 300 mg immediately upon waking to power a morning gym session. Max dose to not disrupt sleep 16 hours later. Even with full tolerance, I definitely get better explosive early morning gym energy than I ever did while abstaining completely.
Theacrine is caffeine's weirdly paradoxical cousin. It stimulates dopamine and blocks adenosine (sleepy) receptors like caffeine. The half-life is insane at 16-33 hours. Yet it's been studied to not build tolerance or disrupt sleep. Strange, I know. At high blood concentrations it stimulates, at low blood concentrations it slightly sedates.
Caffeine and theacrine share a synergy where caffeine dramatically boosts how much theacrine gets absorbed. This makes the stimulative dopamine effects of theacrine more apparent. If you take it alone, the dose you absorb may fall under the stimulative threshold; just making you sleepy instead.
Stacking 100 mg theacrine with my 300 mg morning caffeine dose feels like my caffeine tolerance was deleted. The initial hit is slower than 300 mg caffeine with no tolerance. But after 2 hours, I have laser focus, feel talkative and eating anything feels gross. It's been a struggle getting in post-workout protein lol. The focus boost is also greater than I've ever gotten from caffeine alone. And the energy keeps going for longer, smoothing out the crash from caffeine dropping at 10 hours in. The effect tapers off to not disrupt sleep 16 hours later.
Interestingly, theacrine hasn't been shown to cause tolerance in studies of continued use. There's no withdrawals when you quit and the effect never gets weaker. If my caffeine sensitivity doesn't somehow further degrade with this combination, I assume I can keep using this stack forever and keep getting this same "caffeine honeymoon" effect! As my caffeine tolerance is stable and theacrine apparently doesn't cause tolerance. It's only been two weeks though, and it would seem odd for anything this dopamine-stimulating to not cause brain adaptation.
Most negative anecdotes about theacrine come from users who've attempted to fully replace caffeine with it. I've tried it alone and found its benefits to only be unlocked with a caffeine stack. If you dislike superdosed caffeine, I suggest trying 100 mg theacrine with 100 mg of caffeine. The effect is much greater than 100 mg caffeine alone, without extra jitters or anxiety.
It's like theacrine works as a booster for the positive parts of caffeine. Unlike L-theanine, which dampens the bad parts of a higher dose, theacrine works by adding more of the good stuff to a smaller dose. Allowing you to keep the caffeine at a sensible amount to prevent the bad stuff. Which is obviously better for sleep quality and building less tolerance, than taking a caffeine mega-dose and then dampening it with another supplement.