Glossary

Caffeine Threshold

Updated February 22, 2026

Caffeine threshold is the behaviorally adjusted intake point where side effects become likely enough to reduce decision quality for a given user.

Why it matters

People differ by body mass, metabolism, anxiety baseline, sleep timing, and medication overlap, so one universal cutoff is not useful.

Personalized threshold model

• Define a personal cap using body size, sensitivity history, and whether you are a high-sensitivity responder.
• Use two anchors: time since waking and expected sleep onset.
• If your routine is fragmented or late-shift, cap more tightly and shift all caffeine earlier relative to planned sleep.
• A practical check is symptom response at the same intake over 3 consecutive days.

Symptom checklist for over-threshold states

• palpitations
• anxiety spikes
• GI upset
• persistent headache after intake
• tremor or restless pacing
• unexpected crash and mood volatility

Practical tapering approach

Use a calm rollback when sensitive:

1. Reduce daily caffeine by 25–40% for 3–7 days.
2. Remove one source first (often the late-day source).
3. Keep the same logging discipline for timing, dose, and symptoms.
4. Increase only one layer at a time after baseline stabilizes.

Cross-site references

• Stimulant sensitivity
• Dose logging
• Consistency streaks

Uncertainty

• Evidence is limited for exact body-mass formulas in mixed supplement users.
• Evidence is limited for crossover timing rules in rotating-shift schedules.

How this appears in Unfair

Unfair classifies sensitivity signals and uses these bands to moderate stimulant recommendations and timing suggestions.

Clinical safety note

If chest pain, severe palpitations, syncope-like episodes, or confusion appears, stop caffeine and seek clinical evaluation promptly.