[jwells89]

While I don’t have hard evidence to support the idea, I believe this is highly variable between individuals.

I’m not a heavy coffee drinker, but I do have a cup in the mornings some time between 6:30-8:00. This makes it easy to stop as needed; there are some days where I skip it out of necessity (too busy), and occasionally I’ll go a weekend without it just to keep my tolerance in check. During these periods, I never experience adverse effects.

The main benefit I glean from coffee is not feeling awake, but notably improved ability to focus. In my experience, my baseline ability is just not as good; there’s no “bounce back” after extended periods of going without, it just stays somewhere between bad and average indefinitely.

[NBJack]

I strongly suspect this manifests more in folks that consistently intake > 100mg per day. I used to regularly intake 200mg total across ~2 beverages (mostly because I just enjoyed the flavor), and suffered mild headaches if I skipped my schedule. I know others that start their day with 200mg in a single, quad shot beverage.