After you consume a stimulant, your body clears it exponentially — each half-life period, the remaining amount halves. This app computes that curve and tells you when the level drops below the threshold where sleep is meaningfully affected.
| Substance | Half-life | Source |
|---|---|---|
| Caffeine | 5.5 hr | Nehlig et al., Brain Res Rev 1992 |
| Paraxanthine | 3.5 hr | Arnaud, Food Chem Toxicol 1987 |
Caffeine's sleep threshold is set at 25 mg — the level at which adenosine receptor occupancy becomes negligible and sleep architecture is no longer measurably disrupted. For paraxanthine (caffeine's primary metabolite), 12 mg is used as a proportional estimate.
Landolt et al., Neuropsychopharmacology 1995 · Fredholm et al., Pharmacol Rev 1999
Half-lives vary significantly between individuals based on genetics, liver function, medications, and pregnancy. Values here represent population averages for healthy adults. This tool is for informational purposes only.