Pharmacokinetic half-life simulator. Manage your sleep pressure (Adenosine) and avoid induced insomnia.
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"Caffeine does not generate energy; it is a loan shark. It blocks adenosine receptors today, in exchange for greater fatigue tomorrow."
During wakefulness, your neurons consume ATP. The byproduct is adenosine, which accumulates and binds to receptors, creating "sleep pressure". Sleep is the process of clearing this adenosine.
Caffeine is a competitive antagonist. It has the same shape as adenosine and occupies its receptors without activating them. It's like putting gum in a lock: the key (adenosine) cannot enter, but the door doesn't open.
The half-life of caffeine is ~5.5 hours. If you take 200mg at 2:00 PM:
Those remaining 50mg are the cause of waking up multiple times at night or waking up tired. They drastically reduce Deep NREM sleep, essential for physical recovery.
Not everyone is equal. The hepatic enzyme CYP1A2 degrades caffeine. Genetic variants make some people "fast metabolizers" (can drink coffee in the afternoon) and others "slow" (anxiety with a single cup). This calculator assumes a standard average, but allows adjustments.
Yes, but in tiny amounts (2-5mg). You would need to drink 10-20 cups of decaf to equal one regular espresso.
Wait 90 minutes after waking up. This allows natural cortisol (waking hormone) to do its job and for residual adenosine to clear completely. Drinking coffee immediately upon waking interferes with the cortisol rhythm.