When should you stop caffeine before bed?

By Caff Conscious · Updated October 14, 2026

A useful starting point is the caffeine you actually drank and the bedtime you are planning for. A single clock-time rule cannot describe every dose, schedule, or person.

Why the hours before bed matter

In a 2013 randomized study by Drake and colleagues, adults received 400 mg of caffeine or placebo at bedtime, three hours before, or six hours before. The caffeine conditions disrupted sleep, including the six-hour condition. This study tested a substantial fixed dose; it does not establish one cutoff for every drink or person.

A timing calculator answers a narrower question: what amount remains under a chosen half-life assumption? It cannot translate that amount into a guaranteed sleep outcome.

Compare earlier and later drinks

For a hypothetical 100 mg drink, an 11 PM bedtime, and a five-hour half-life, the same equation produces these estimates:

These are calculations, not recommended intake levels. They exclude other drinks and assume immediate absorption. A later drink leaves more caffeine at the same bedtime under those assumptions, while a smaller starting amount reduces the estimate proportionally.

Compare your drink and bedtime

Keep the assumptions visible

Record the serving, caffeine amount, and drinking time. Use your intended bedtime rather than a default that does not fit your schedule. If bedtime is after midnight, choose the next day in the calculator. If an amount is uncertain, treat the result as uncertain too.

Half-life is another assumption. Our half-life guide shows how an amount falls over time and why a drink can still contribute to the estimate many hours later.

A daily amount is not a bedtime cutoff

The FDA’s general guidance on caffeine describes differences in sensitivity and elimination and discusses daily intake. A daily quantity does not identify a universal amount that is safe for sleep at bedtime. Your health context also matters; discuss concerns involving conditions, medications, or pregnancy with a health professional.

Keep a log, then look for patterns

In Caff Conscious, log what you actually drank, check the amount and time, and set your target bedtime. The app estimates remaining caffeine from the recorded drinks. Optional Weekly Insights supports looking back at patterns. Neither a pattern nor an estimate diagnoses a sleep problem or proves what caused a particular night’s sleep.

For a single-drink illustration, use the free calculator above. Its method and limitations explain exactly what goes into the number.

Sources

• Drake et al. (2013), Caffeine Effects on Sleep Taken 0, 3, or 6 Hours before Going to Bed, Journal of Clinical Sleep Medicine.
• FDA: Spilling the Beans — How Much Caffeine Is Too Much?

This guide is educational information, not medical advice or a personalized caffeine cutoff.