HALF-LIFE GUIDE

Three hours, five hours, or eight?

Half-life is the most influential assumption in the model—and one of the hardest to know precisely for an individual.

The difference compounds

Ten hours after a 100 mg dose, about 10 mg remains with a three-hour half-life, 25 mg with a five-hour half-life, and 42 mg with an eight-hour half-life. A small slider change can therefore materially alter the bedtime estimate.

Why people differ

Caffeine clearance is influenced by genetics, pregnancy, smoking, liver function, age, and some medications. StimTrace does not infer a personal half-life from medical questions. Instead, it keeps the assumption visible and adjustable.

Use trends, not false precision

Choose a reasonable value, log consistently, and compare the estimate with your experience. The weekly view can reveal whether earlier last-caffeine times line up with better nights, without claiming to diagnose the cause.