Caffeine
health · my rules, and why
Rule: none after 2 pm.
Why
- Caffeine works by blocking adenosine, the molecule behind sleep pressure. You feel less tired, but the pressure is still building underneath.
- Its half-life is roughly five to six hours for most people. A 3 pm coffee can still be about half active at 9 pm.
- Even when I fall asleep fine, late caffeine seems to make the night lighter. My watch shows less deep sleep on those days.
What counts
| Drink | Rough caffeine |
|---|---|
| Espresso | 60 to 80 mg |
| Filter coffee, large mug | 120 to 180 mg |
| Black tea | 40 to 60 mg |
| Green tea | 25 to 40 mg |
| Cola, one can | about 35 mg |
These vary a lot by brand and brew. Treat them as ballpark numbers.
What I do instead
- After 2 pm: decaf, herbal tea, or sparkling water.
- On heavy training days I have my coffee about an hour before the session, and never for an evening session. See training.