About

This is not a simple counter; it is a pharmacokinetic simulator designed to prevent sleep disruption. Caffeine is a unique compound with a variable half-life that allows it to persist in your system long after the psychological effects have faded. While you may feel "tired" at 10 PM, your adenosine receptors may still be blocked by residual caffeine consumed at 2 PM.

This tool utilizes a First-Order Absorption and Elimination model. It accounts for your specific metabolic sensitivity (CYP1A2 enzyme activity) to visualize exactly how much caffeine remains in your plasma. By pinpointing the moment your levels drop below the 50mg Sleep Threshold, you can make data-driven decisions about that afternoon espresso.

Formulas

The core mechanism relies on exponential decay mathematics. While absorption is rapid (peak levels ≈ 45 mins), elimination is slow. We calculate the residual mass M at time t using:

M(t) = Dose ⋅ (0.5)^{t − t_intakeT_1/2}

Where T_1/2 represents the biological half-life. The algorithm dynamically sums overlapping curves for multiple doses:

Total(t) = n∑i=1 M_i(t)

We define the Sleep Threshold as Total < 50mg. Above this level, clinical data suggests statistically significant latency in sleep onset (SOL).

Reference Data

Beverage / Item	Volume	Caffeine Content (mg)	Sleep Impact Risk
Espresso & Coffee
Starbucks Pike Place Roast	16 oz	310	EXTREME
Dunkin' Original Blend	14 oz	210	HIGH
Espresso (Single Shot)	1 oz	63	MODERATE
Nespresso Capsule (Original)	1.35 oz	60	MODERATE
Cold Brew (Generic)	12 oz	200	HIGH
McDonald's Coffee	16 oz	145	HIGH
Energy Drinks
Red Bull Original	8.4 oz	80	MODERATE
Monster Energy	16 oz	160	HIGH
Celsius	12 oz	200	HIGH
Bang Energy	16 oz	300	EXTREME
5-Hour Energy Shot	2 oz	200	HIGH
Tea & Soda
Coca-Cola Classic	12 oz	34	LOW
Mountain Dew	12 oz	54	LOW
Diet Coke	12 oz	46	LOW
Black Tea (Brewed)	8 oz	47	LOW
Matcha (Ceremonial)	1 tsp	70	MODERATE
Yerba Mate	8 oz	85	MODERATE

Frequently Asked Questions

Scientific consensus suggests that for most adults, having less than 50mg of active caffeine in the bloodstream minimizes sleep disruption. Above this threshold, caffeine binds to adenosine receptors, physically preventing the brain from receiving "tiredness" signals.

It is a crucial estimation. "Normal" assumes a 5-hour half-life. "Sensitive" (slow metabolizers) extends this to 7+ hours, often due to CYP1A2 gene variations, age, or oral contraceptive use. "Resistant" (fast metabolizers) assumes ~3.5 hours, common in heavy smokers or those with specific genetic markers.

This is the "Caffeine Crash" paradox. The psychological "buzz" (dopamine/adrenaline) wears off much faster than the drug is eliminated from your blood. Even if you feel tired, the physical molecule is still circulating and disrupting your deep sleep (REM) cycles.

Yes, slightly. Consuming caffeine with a heavy meal can delay peak blood concentration by 15-60 minutes, but it does not significantly change the total elimination half-life. The caffeine must still be processed by the liver.

The FDA and EFSA recommend a limit of 400mg per day for healthy adults (approx. 4 cups of coffee). Doses exceeding 1,000mg can induce toxicity symptoms including arrhythmia, muscle tremors, and confusion.