Caffeine Curfew
No caffeine after ~2pm (for 10pm bedtime). Caffeine's 5-6 hour half-life means afternoon intake significantly reduces deep sleep even if you fall asleep fine.
Dosage & Timing
Evidence Strength
5/5 — Very StrongVery strong evidence. Caffeine's mechanism (adenosine receptor antagonism) and pharmacokinetics are thoroughly established.
Overview
Stop consuming caffeine at least 8-10 hours before your target bedtime. Caffeine has a half-life of 5-6 hours, meaning that even afternoon coffee can significantly disrupt sleep architecture, particularly deep sleep.
How To Do It
Calculate your curfew
Subtract 8-10 hours from bedtime. For a 10pm bedtime, stop caffeine by noon-2pm.
Audit hidden caffeine
Watch for caffeine in tea, chocolate, pre-workout, and some medications.
Delay morning caffeine
Wait 90-120 min after waking for your first caffeine to avoid afternoon crash and dependence.
The Evidence
Each claim is linked to its source study. Confidence reflects the study design — systematic reviews and RCTs rank highest.
Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed↗
Caffeine consumed even 6 hours before bedtime significantly disrupted sleep.
Primary Literature
Who Popularized This
Interactions & Warnings
Interactions
- •Foundational for all sleep optimization
Measurable Outcomes
Related Protocols
Morning Sunlight Exposure
View bright light within 60 minutes of waking to set your circadian clock. This triggers a cortisol pulse and starts a timer for melatonin release 14-16 hours later.
Sleep Temperature Optimization
Keep your bedroom at 65-68°F and take a warm shower 1-2 hours before bed. Core temperature drop is a key trigger for sleep onset and deep sleep.
Glycine for Sleep Quality
3g glycine before bed lowers core temperature and enhances deep sleep. Studies show improved next-day performance even with restricted sleep.
Consistent Wake Time
Set one wake time and stick to it 7 days/week. This anchors your entire circadian system more reliably than any other single habit.