A common rule-of-thumb is to avoid substantial caffeine within ~6 hours of bedtime. For many people, going earlier works even better.
Even earlier caffeine can carry into bedtime. If falling asleep is hard, earlier timing is an easy variable to test.
If you’re sensitive, anxious, or prone to insomnia, try 8–10 hours as an experiment — and compare outcomes.
Use the cutoff calculator with a higher sensitivity tier and lower bedtime target, then iterate based on results.
No. This guide is educational. If you have health concerns or take medications, talk to a clinician.
Use the tools first, then come back here if you want the “why” behind the numbers.