SYSTEMM · CALCULATORSV1 · LIVE
VII · STIMULANT · CAFFEINE
Caffeine half-life.
Dose, time, your personal half-life. How much caffeine is still in you when you try to sleep.
InputsLive
Dose
mg
Consumed At
Half-Life
hours
Bedtime
Metabolizer Type
Source
OutputsLive
Caffeine At Bedtime
25
mg · still in system
Visual · Exponential Decay
Details
Peak Plasma
30 – 60
min post-dose
Below 50 mg At
15:20
effectively gone
% At Bedtime
12%
of original dose
Last Safe Sip
16:00
for clean sleep
Math · Exponential Decay
01 · Hours Until Bedtime
23:00 − 08:00
= 15 hours
02 · Half-Lives Elapsed
15 h ÷ 5 h
= 3.0 half-lives
03 · Remaining Caffeine
200 mg × 0.5³ = 200 × 0.125
= 25 mg
→ At Bedtime
Notes
Half-life is 5 h average. CYP1A2 slow metabolizers run 8 – 10 h. Pregnancy doubles it.
Caffeine still affects deep sleep at 25 mg. Aim for under 50 mg by sleep onset.
Cut-off rule: last caffeine at least 8 – 10 hours before bed for clean architecture.
Tolerance moves wake response, not sleep impact. The receptors that ruin sleep don't down-regulate.
For educational purposes only. Individual caffeine metabolism varies significantly with genetics, medications, age, pregnancy, and liver function. Consult a physician about caffeine intake in health-sensitive contexts.