The Caffeine & Sleep Guide

Your 2 p.m. coffee is still 29% active at 11 p.m. — and in the study that measured

it, people lost over an hour of sleep to afternoon caffeine **and could not feel it

happening**.

This is the complete system for fixing that without giving up coffee. Nothing here

asks you to quit. It asks you to know your dose, know your clearance speed, and put

one time on the clock.

**WHAT YOU GET (3 downloads)**

📘 **The Guide — 38 pages, one idea per page, every claim sourced**

- The mechanism: why caffeine has zero energy in it, and what it actually does

- Your clearance: the 3-to-7-hour half-life, the CYP1A2 enzyme, and the 40-fold

  difference between people (this is why "coffee doesn't affect me" and your

  insomnia are both true)

- The measured cost: the Drake 2013 study, and why you cannot feel the damage

- The source guide: coffee, espresso, tea, energy drinks, pre-workout and decaf,

  with working numbers — including the café problem (an "Americano" can carry six

  times the caffeine of a "pour-over")

- The strategy: the six-hour rule, personalized to your body

- The 5-day tolerance reset: get the effect back at half the dose

📊 **The Cutoff Calculator (Excel + Google Sheets)**

Log your day's drinks and it computes your total load, the milligrams still active

at your bedtime, a plain-English verdict, and **your personal cutoff time** — from

your own clearance class, not an average. With a live decay-curve chart of your day.

🖨️ **The Printable Toolkit (3 pages)**

- The 3-Night Speed Test — find your clearance class with pen and paper

- The Cutoff Card — fill it in, stick it where the kettle lives

- The 5-Day Reset Tracker — tick boxes, symptom log, re-entry rules

**WHO IT IS FOR**

Anyone who drinks caffeine, sleeps badly, and refuses to choose between them.

Works with or without a sleep tracker (Oura, Whoop, Garmin and Apple Watch owners

get extra mileage from the verification steps).

**THE HONEST PART**

Every figure in the guide names its study on the page. Where the evidence is weak —

the crash mechanism, tolerance in humans, the viral "delay your morning coffee"

rule — the guide says so and grades it. That is the SleepMetric standard: science-

backed sleep for real life.