Caffeine cut-off calculator: when to stop for better sleep
Caffeine stays active for hours after your last cup. Enter your bedtime and your usual drink to see the latest time to have it, based on a 2023 review of the research on caffeine and sleep.
Your evening
When do you usually go to bed, and what do you usually drink?
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at the latest
These are averages from sleep studies, not a rule for everyone: some people clear caffeine faster or slower than others. If you want a simple rule, many people find "no caffeine after midday" easy to remember.
Try your cut-off for two weeks
- Caffeine in a tap. Log how many cups you had alongside your day, with alcohol, spicy food and stress if you like.
- Sleep without effort. Rate each night in a tap, or import it from Apple Health or Health Connect.
- See what lines up. PeriFlow points out when caffeine seems to go with worse sleep or more hot flushes on your own days.
Why the gap is so long
Caffeine works by blocking adenosine, the chemical that builds up through the day and makes you sleepy. It is cleared slowly, so a mid-afternoon coffee can still be working when you go to bed, even if you fall asleep easily.
That last point catches people out: falling asleep easily doesn’t mean you slept well. In a placebo-controlled study, a strong dose of caffeine (400 mg) taken six hours before bed still significantly disrupted sleep and shortened it. A 2023 review that pooled the research put the gap needed to avoid losing sleep at 8.8 hours for a regular coffee, and 13.2 hours for a dose of about 200 mg, such as a pre-workout supplement.
In perimenopause, when sleep is often already broken by night sweats or early waking, that lost sleep is harder to absorb. Our guide to perimenopause sleep problems covers the other things that help.
Caffeine and hot flushes
Some women notice that coffee seems to set off hot flushes. The research here is limited: one study of postmenopausal women found that higher caffeine intake was linked to more bothersome hot flushes, but a link like that can’t show cause. Tracking your own caffeine and hot flushes for a few weeks is the most reliable way to see whether it applies to you. See also what helps with hot flushes.
Frequently asked questions
How long before bed should I stop drinking coffee?
Longer than most people think. A 2023 review of the research found that a regular cup of coffee (about 107 mg of caffeine) shortened total sleep unless it was drunk at least 8.8 hours before bed. For a dose of about 200 mg the gap was 13.2 hours (the review’s example was a pre-workout supplement; a large coffee, a double shot or an energy drink can contain a similar amount). For a 10:30pm bedtime, that means a last regular coffee by about 1:30pm.
Does caffeine make hot flushes worse?
It might for some women, but the evidence is thin. One study of postmenopausal women found that those who drank more caffeine reported more bothersome hot flushes. That shows a link, not that caffeine causes them. The most reliable way to find out for yourself is to track caffeine and hot flushes side by side for a few weeks.
Does tea count?
Yes. Tea usually has less caffeine than coffee, so the gap can be shorter, but no study has set a separate time for it. Green tea, cola, energy drinks and dark chocolate also contain caffeine.
Is decaf fine in the evening?
Decaf still contains a little caffeine, but far less than regular coffee, so for most people it is much less likely to affect sleep.
Why does caffeine seem to affect my sleep more now?
Many women find their sleep becomes lighter and more easily broken in perimenopause, with night sweats and early waking adding to it. When sleep is already fragile, anything that shortens or lightens it matters more, so a cut-off that never mattered before can start to.
More free tools
Perimenopause symptom checklist: tick what you've noticed and get a list to take to your doctor.
Perimenopause protein calculator: how much protein you need a day, and per meal.
Calcium checker: a rough estimate of your daily calcium against the reference intake for your age.
Sources
- Gardiner C, et al. The effect of caffeine on subsequent sleep: a systematic review and meta-analysis. Sleep Med Rev. 2023. PubMed
- Drake C, et al. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med. 2013. PubMed
- Faubion SS, et al. Caffeine and menopausal symptoms: what is the association? Menopause. 2015. PubMed
This calculator gives general information about caffeine and sleep, not medical advice. If you are pregnant, take regular medication, or have a heart rhythm condition or anxiety disorder, ask your doctor or pharmacist about caffeine. If poor sleep is affecting your daily life, it’s worth talking to a doctor.