Is 6 hours before bed always enough?

Not for every person or dose. A study using 400 mg found sleep disruption even at six hours before bedtime. It doesn't establish one cutoff for smaller drinks.

Should the cutoff move when bedtime moves?

Yes. Use the bedtime you expect that night. A later bedtime gives earlier drinks more time to clear.

What if I already had caffeine this afternoon?

Log it at the time you had it, then look at the bedtime estimate before you add another serving.

Does a cutoff guarantee sleep?

No. It is a planning estimate based on the serving and selected assumptions. It cannot predict all the influences on sleep.

Guide

When to Stop Caffeine Before Bed

There is no single cutoff for every dose and person. Use your bedtime, the size of the drink, and a study of 400 milligrams taken 6 hours before sleep.

Updated October 15, 2026 2 min read

Caffeine Tracker is free to download.

Short answer

Stop at a time that fits your bedtime and the size of the drink, then adjust from how you slept. There is no one clock time for every person. In one study, 400 milligrams of caffeine still disrupted sleep when people took it 6 hours before bed.

A 2 pm cutoff means something different to someone going to bed at 9 pm than to someone sleeping at midnight. The serving size matters too. Record the amount, the time, and the intended bedtime before comparing an afternoon drink with an earlier one.

Compare timing with one fixed assumption

Example 100 mg serving	Time until an 11 pm bedtime	Estimated remainder
1 pm	10 hours	25 mg
6 pm	5 hours	50 mg

These are arithmetic examples using a five-hour half-life. The dose is the same, but the later drink leaves twice as much in the model at bedtime. The figures are estimates, rather than sleep predictions or recommended targets.

Write down bedtime, dose, and time

Start with the time you usually get into bed, including the later bedtime you actually keep on some nights. Then note the drink, the serving, and when you finished it. A bedtime estimate is only as complete as that list.

Include sources that do not feel like coffee. Soft drinks, tea, energy drinks, shots, gum, and caffeine supplements all belong in the total if you want the number to mean anything. Group the day around the bedtime it leads into, so a late drink stays with the night it can affect.

Test a cutoff against a known dose

A 2013 placebo-controlled study of 400 mg doses found sleep disruption when caffeine was taken at bedtime, three hours before, and six hours before. That is evidence about a particular dose and study, rather than a universal cutoff for every drink.

A smaller serving and a different bedtime change the comparison. Record the dose and time before deciding whether another serving fits your plan. An app’s estimate still cannot tell you how the night will go.

Change one thing and review it

Keep a simple record of when you had caffeine and how the night felt. If you move the last serving earlier or reduce its size, record that change too. Sleep has many influences, so avoid treating one better or worse night as proof of the cause.

If you are pregnant, trying to become pregnant, breastfeeding, or managing a condition or medicine that concerns you, ask a health care provider about limiting caffeine. Use an app cutoff as a planning figure, and have that clinical conversation separately.

Check the next serving against your bedtime

Caffeine Tracker estimates how many milligrams may remain at your usual bedtime and compares that figure with your bedtime target. When another serving of a logged drink fits both that target and your remaining daily allowance, it can show an estimated latest time for that serving.