Living document, last updated: 2026-08-14
Tim Ferriss shared a quote from Roland Griffiths, a leading researcher on caffeine: “You can never understand your relationship to a drug, to a psychoactive substance, unless you get off it and stand back and look at it.”
Ferriss’s conversation with Griffiths, in turn, inspired an experiment where Ferriss went caffeine-free for a period of three months and then re-oriented his relationship with caffeine.
It’s safe to say that caffeine is my favorite drug, my most-used drug, and one that I have a tendency to abuse regularly. And that’s not uncommon; caffeine is the most consumed psychoactive substance in the world.
In light of that, I might not have given it a second thought, because culture sometimes bundles excessive coffee drinking under the umbrella of so-called “healthy addictions” and even normalizes or glorifies its use.
However, there were two major contributors that made me want to start looking into this more closely.
The first was the quest to optimize my sleep. As I addressed many of the other common lifestyle and environmental interventions, I couldn’t figure out why my sleep latency, architecture and overall quality was sometimes worse than it seemed it should have been. I tried following the advice to “stop drinking coffee by 2PM” and was still getting random days of sleep data results worse than I would have expected.
The second thing was my troubling personal experience with negative side effects like massive anxiety, energy crashes, heart palpitations, and cravings from time-to-time, usually worse in summer during cold brew season. These are occasionally so rough that it made me want to find a solution.
So here’s the thing: I’m not quitting coffee. I love everything about it; the taste, the culture, the science, the history, and the ritual. I believe it has real, tangible benefits. But I realized that the standard advice about caffeine consumption was failing me, solutions like r/decaf are all-or-nothing thinking, and at the end of the day this is basically a math problem.
So that means that it’s time to optimize, and there’s a calculator below so you can run your own numbers.
The problem based on a typical day (case study: me)
Here’s what a typical day of caffeine consumption might look like for me.
I wake up at 5AM, get moving, train, and delay my first caffeine intake by 60 to 90 minutes. If I have a heavy lifting day, I might start drinking coffee intraworkout; otherwise I wait until breakfast around 6:30am. Usually I kick things off with an iced double espresso.
Then, after I get cleaned up and moving the morning forward, I’ll have another coffee (16 oz drip or another iced double shot) on the way to dropping the kids off, and that might last until I start working.
Depending on where I’m working that particular day, I’ll have some more coffee (usually 8-12 oz drip or 16-20 oz cold brew) over the next 90 minutes or so.
Based on how the day and my work is going, I might have a late morning bump. Otherwise, I’ll typically make it until early afternoon-ish when I take a post-lunch hit (more drip or cold brew likely).
If things are going exceptionally poorly on a given day, I might consume even more caffeine (perhaps a Zevia cola or iced tea) before I pick the kids up to combat my low energy, and top it all off with some 100% cacao dark chocolate after dinner as my treat.
Some days are better, some days are worse, but what I’m ultimately looking for is cognitive performance, physical training benefits, and appetite suppression.
The negative aspects to my caffeine use are the mindless habitual use, using it as a crutch when my energy or mood dip, and mindless sipping when I’m probably just dehydrated or hungry. It’s become clear to me that the tax I pay for this redline-then-crash cycle is real, and I want to fix it.
Why the standard advice fails
Experts such as Andrew Huberman, Matthew Walker, Bryan Johnson offer similar advice on the appropriate caffeine consumption cutoff window:
- “Aim to stop caffeine intake at least 8-10 hours before your expected bedtime” –Huberman
- “Caffeine has a five to six hour half-life in your bloodstream” –Johnson
- “Aim to drink your last cup by 11 AM” –Walker
However, the standard advice failed me because it’s usually being offered under the assumption that people are consuming moderate amounts of caffeine. The advice to take your last sip of coffee by 2 PM might work if you’re going to bed at 10 PM and you had only 2-3 standard (6 oz.) cups of coffee throughout the morning.
You can stop by noon, but if that stop is a double espresso at 11:59 on top of a morning of cold brew, the total circulating load and its decay curve are what matter. You can be “compliant” with the standard advice and easily exceed 50mg of caffeine at lights-out.
Although there is often mention of the half life of caffeine (5-6 hours and dependent on an individual’s genetics and other factors) in these discussions, as of yet I haven’t seen any real guidance surrounding the dose and timing and how those impact both caffeine clearance and the levels of caffeine still circulating in your bloodstream at bedtime.
What I’ve concluded so far is that you should use the least amount of caffeine necessary, not the most possible. If you generally want to get better quality sleep, and more of it, it’s time to dive deeper into the details of caffeine pharmacokinetics.
What I found when I ran my own numbers
When I started to model my own typical coffee consumption curves in a crude, early version of the tool in this post, I began to realize how much trouble I was in.
(Side note: I previously used a test to determine that genetically speaking, I am an average caffeine metabolizer.)
What I found is that it was common for me to have 100-200mg or more routinely circulating in my bloodstream late into the night, sometimes past midnight. On peak days, it was unlikely that I was reaching full clearance before waking the next morning.
This was leading to a vicious cycle: wake up with ~50mg of yesterday’s caffeine still aboard and feel “below baseline” partially due to withdrawal, and partially due to blunted sleep. This led me to pound more on top of the residual, intra-day crashes, more use to try and stabilize, and ultimately my body never reaching homeostasis or its natural circadian rhythm.
In my sleep data, this is presented as a higher average resting heart rate, a lower HRV, higher sleep latency, lessened blood pressure dip, and sub-optimal sleep architecture with either my curve shifting later in the night, and less deep/slow-wave sleep. Anecdotally, this also led to more restlessness and frequent wakeups in the night.
What “optimized” looks like
At the end of the day, there is one benchmark that matters, and that is achieving near-zero (and absolutely under 50mg) of caffeine in the bloodstream when your head hits the pillow.
I want to continue to enjoy my coffee ritual each day, but I want to stop paying the hefty tax associated with overuse and dependence. I will optimize my way toward alertness, physical training benefits, cognitive lift for deep work, and any of the other bioprotective mechanisms that might be in play.
I will reverse the dependence cycle into a virtuous cycle: clear the caffeine fully before bed, fall asleep fast and sleep well, wake up genuinely restored, and need less tomorrow.
The other interesting thing about optimizing both the dose and timing of this powerful enhancement drug is that it also forces you to schedule the activities it enhances, both deep work and training, around the time you’re enjoying it. Front-loading these activities in the morning is aligned with my ideal lifestyle, anyway, and better fits the natural circadian rhythm.
The caffeine clearance calculator
After I realized that this was a math-based optimization problem, I searched for a tool online and I couldn’t find anything satisfactory. The best option was basically “is this too much caffeine?” calculator with very basic inputs. So I vibe coded this caffeine clearance calculator to scratch my own itch.
This is the fun part, because everything I shared up until this point is just my experience. This is where it becomes your data, and the point at which you can begin running some experiments of your own.
How to use it
Start with the Load Sample Day button to see how the model works. Then clear it and recreate yesterday — honestly. That’s the whole exercise.
- Set your bedtime and your half-life. If you don’t know your half-life, start at the 5-hour average. Roughly half of us are slow metabolizers (closer to 6–7 hours) thanks to CYP1A2 gene variants; fast metabolizers sit nearer 3–4. The tool explains how to adjust it based on how your sleep responds.
- Log your doses. Every one — the espresso, the “cup” of coffee that’s really 16 ounces, the afternoon iced tea, the pre-workout scoop. Undercounting here is just lying to yourself with extra steps.
- Add your activity windows (optional). Mark when you train and when you do your deepest work, and you’ll see whether your caffeine peak actually lines up with the moments you’re taking it for. Mine didn’t.
- Read the “At Bedtime” number. Then check it against the sleep-impact tiers. Under 25 mg, you’re largely in the clear. At 50–100 mg, research suggests your deep sleep can be reduced 10–20% — even when falling asleep feels normal. That last part is the trap: you don’t feel the damage, so you never connect the 2 PM cold brew to the flat, groggy morning that follows.
The first time I ran my own typical day through an early version of this tool, my bedtime number wasn’t 25 mg. It wasn’t 100 mg. Some days it was north of 200 mg — the equivalent of drinking a fresh cup of coffee, turning off the lights, and expecting a great night of deep sleep. That was the moment this whole experiment started.
What the model is and isn’t
This is intended to be a tool and a model, and it has some limitations that you need to be aware of. For me, it’s been helpful directionally, as a map of what’s probably going on in the big picture. As much as I want to take this all the way to the highest, most perfect form I can imagine, I don’t think that’s realistic or worthwhile right now.
For example, real life isn’t a bolus dose at t=0 (maybe for a single shot of espresso). Usually you sip a coffee at your desk for 45 minutes, and that’s part of the simple pleasure.
So here’s a little bit of a deeper explanation and disclaimer that I drafted with the help of A.I.:
This is a simplified single-compartment pharmacokinetic model. Each dose decays exponentially — C(t) = dose × 0.5^(elapsed ÷ half-life) — and all active doses are summed at every point in time. It assumes caffeine hits your bloodstream instantly, when in reality it peaks 30–60 minutes after you drink it. For bedtime planning that assumption is actually conservative (it errs toward overestimating what’s left in your system), but it means the rising edge of the curve is slightly idealized. The drink presets are population averages, and real-world caffeine content varies a lot by brand, brew method, and pour size — a coffee-shop cold brew can quietly double a homemade cup.
And the obvious one: this is an educational tool, not medical advice. Caffeine sensitivity varies with genetics, body weight, tolerance, medications, pregnancy, and underlying health conditions. If any of those apply to you — or you’re managing a sleep, cardiac, or anxiety condition — talk to an actual professional before you start experimenting.
My protocol and what I’m actually testing
Based on what I’m observing in playing around with the clearance calculator, I’ve tried to come up with some principles and practices that I’m testing and collecting data on.
For a number of years, I’ve been pretty consistent at delaying forest caffeine for 60-90 minutes after waking, and I’m keeping that up.
So from there, I’m attempting to front-load my biggest dose early, and then taper down. I’m currently stopping all caffeine intake after 12 PM, and I’m using the “substitution” strategy (by switching to decaf) or using sparkling water if I just need a sensory hit.
I am sitting with the urge to drink coffee when it comes, and checking in with myself: “am I actually just thirsty, hungry or tired?” If the answer is yes, I try to meet that need in a different way than more caffeine.
I’m aligning deep work in the morning, as I have also done really well for a long time, to coincide with peak concentration levels in my bloodstream.
Finally, I’m also capping my overall intake to a maximum of 400mg per day.
One “known issue” is that I sometimes train at ~5AM, and this has been a little variable lately. On the days that I do, especially if I’m lifting heavy, the lack of caffeine during those times is a bit of a challenge. In the past, I budged on my wake-up delay, and maybe that is OK as long as I stick within my other boundaries; further testing will be conducted and a verdict rendered down the road.
What I’m measuring in my own experimentation
In my own n=1 experiment, I’m tracking a handful of inputs and outputs and plan to report back with any patterns or findings that I observe after I gather sufficient data.
My inputs include the caffeine intake: date, start time, end time, item, estimated caffeine content (in milligrams).
My outputs include sleep data like latency, total sleep, deep sleep, REM sleep, resting heart rate, HRV, sleep timing, and estimated overnight blood pressure change.
I may begin collecting some subjective, qualitative data as well for things like mood, energy, and notes about how I feel and if there were any potential co-founds on that day (training, major physiological stress events, etc)
Experiment logs (coming soon)
In the future, this will contain a baseline and entries during my experiment periods.
Try it yourself
If you’ve ever been curious or suspect you could improve your relationship with caffeine to increase your overall wellness, I invite you to run your own numbers and report back in the comments section.
Please share the calculator with a caffeine lover in your life if you found this helpful! As for me, coffee remains my favorite beverage and now I’m using it on purpose.