Caffeine & sleep
concept · updated
Two molecules explain most of what caffeine does — and give you a couple of free levers.
Adenosine — the sleep-pressure molecule
- Adenosine builds up through the day and creates “sleep pressure”; sleep clears it (Coffee).
- Caffeine blocks adenosine receptors (15–20 min after drinking), so you feel less sleepy — but the adenosine is still there, waiting.
- Delay coffee ~90 minutes after waking (Andrew Huberman): let your body clear the overnight adenosine first. Drink it immediately and you just park the tiredness for an afternoon crash.
Cortisol — the alertness hormone
- Cortisol naturally peaks ~2 hours after waking. Caffeine makes it rise faster and sooner, and you build tolerance — which is why people creep up to more cups to get the same alertness (Coffee).
- Michael Pollan’s note: quit for ~3 months and caffeine hits like a drug again.
Sleep itself
Sleep pressure is adenosine (Head Strong on sleep). Two adjacent levers from the reading:
- Blue light at night burns mitochondrial energy, drives free radicals in the eyes, and ages skin — cut screens late.
- Cold, meditation, and HRV breathing down-regulate the stress response before bed. See hormesis.