Codex · Rest
Established evidence · well-replicated human evidence
The Caffeine Curfew
Caffeine within ~8 hours of bedtime measurably degrades sleep — often without you noticing, which is exactly the problem.
How it works
Caffeine blocks adenosine, the molecule that accumulates as sleep pressure. Its half-life averages 5–6 hours: a 4 pm coffee leaves a quarter-cup circulating at midnight, trimming deep sleep even when you fall asleep fine. Degraded deep sleep then dulls next-day energy — inviting more caffeine. That loop quietly taxes skin repair and mood too.
The practice
Set a personal curfew ~8–10 hours before bed (for a 10:30 pm sleeper: last caffeine by 1–2 pm). Afternoon replacement: tulsi tea, a 10-minute walk, or a 6-minute Yoga Nidra — all address the dip caffeine only masks.
The tradition
Sleep science
Cautions
- ⚠ Slow metabolizers (sleep-sensitive people) may need a longer curfew.
Related in the Codex
Bhramari — Humming-Bee Breath
Humming on the exhale in small trials reduces anxiety scores and slows heart rate.
The 4-7-8 & Extended-Exhale Breath
Breath patterns with exhales longer than inhales down-shift arousal in most people who try it and prepare the body for sleep.
The Sattvic Plate
Fresh, whole, minimally processed food eaten calmly builds steady energy and clear skin; heavily processed and stale food dulls both mind and complexion.
Ashwagandha — The Steadying Root
Ashwagandha meaningfully lowers perceived stress and cortisol and improves sleep quality in randomized trials.
General wellness information for educational purposes — not medical advice, diagnosis, or treatment. Evidence grades are Cheerayu's honest reading of the literature at the time of writing. Speak with a qualified clinician about your own situation, especially if you are pregnant, nursing, taking medication, or managing a condition. Terms.