How much caffeine at bedtime will disrupt sleep?

Sleep medicine research shows that even 30 to 50 mg of active caffeine in the bloodstream can delay sleep onset and reduce restorative slow-wave deep sleep.

Updated: August 2026 • Verified v1.2

Caffeine Half-Life & Sleep Bloodstream Calculator

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Caffeine(t) = Ingested_mg * 0.5^(Elapsed_Hours / 5.7)

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Understanding Your Results

Calculates active caffeine milligrams remaining at bedtime using the 5.7-hour biological decay formula, rates sleep disruption level, and predicts the exact hour when bloodstream levels drop below the 25 mg restorative threshold.

Practical Guidance & Next Steps

Caffeine blocks adenosine receptors; keeping bedtime bloodstream levels below 25 mg promotes restorative Slow-Wave deep sleep.

What is this?

A circadian health utility that tracks caffeine clearance rates to protect sleep quality.

How does it work?

1. Pick your beverage preset (coffee, espresso, energy drink) or enter mg. 2. Enter consumption time and planned bedtime. 3. View remaining milligrams at bedtime, sleep impact risk, and clean-clear hour.

Why use it?

Reveals why that 3 PM latte keeps you tossing and turning at night.

Technical Scope & Calculation Limitations

Models standard human caffeine clearance rates (average 5.7-hour half-life). Individual liver metabolism may vary based on CYP1A2 genetics.

Frequently Asked Questions

For most healthy adults, the biological half-life of caffeine is approximately 5 to 6 hours (average ~5.7 hours). If you drink 200 mg at 2 PM, about 100 mg remains at 7:45 PM and ~50 mg remains at 1:30 AM.

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