When should you stop drinking coffee before bed?

Short answer: for a regular mug of filter coffee and an 11 pm bedtime, around half past three. For a single espresso, as late as 7 pm. For a flat white, half past one. For a 500 ml Monster, before noon.

The spread is the point. Advice like "no coffee after 2 pm" treats every cup as the same size, and the cups people actually drink range from 44 mg to 200 mg. Work from your drink and your bedtime instead.

Try it with your drink

Half-life 5.7 h · peak at 45 min · sleep threshold 40 mg

Drink

When you had it

Bedtime

Metabolism

Fast Average Slow

At bedtime

—mg

Below 40 mg at

—

Latest for tonight

—

Cira runs this on every drink you log and tells you the hour to stop. Get Cira free →

Why the number is seven to eight hours

Caffeine leaves the body on a half-life curve. For a healthy adult the half-life is typically 5 to 6 hours, and this site uses 5.7 hours: whatever is in your blood now, half is still there 5.7 hours later, a quarter after 11.4 hours, an eighth after 17.

Cira treats 40 mg of active caffeine as low enough to sleep on. It is a working line, not a clinical standard, but it lands close to the research: a review of 24 studies puts the cut-off for a cup of coffee at 8.8 hours before bed, and this model gives about 8 for the same cup.

Put the two together and a 96 mg mug needs about seven and a half hours to drop under 40 mg. An espresso at 64 mg needs only four, because it starts so much closer to the line. A 180 mg cold brew needs twelve and a half.

The cup size matters more than the clock. A double espresso at 4 pm and a filter coffee at 2 pm land in the same place by bedtime.

Last-cup times for common drinks

All for an average metabolism and an 11 pm bedtime, aiming to be under 40 mg by then.

Fast, average or slow

The CYP1A2 enzyme in your liver does most of the work of clearing caffeine, and how active it is varies enormously between people. Half-lives in healthy adults run from about 4 hours to 9 hours, which moves every time in that table by two hours in either direction.

• Fast. Evening coffee rarely stops you falling asleep. You can push the times above later by roughly two hours. Your sleep may still be lighter than it would be otherwise.
• Slow. A coffee after lunch ruins the night. Subtract two to three hours: your last filter coffee for an 11 pm bedtime is around noon.

Some of this is genetic and fixed, and some of it you change without noticing:

• Oral contraceptives roughly double the half-life. The same afternoon coffee becomes an evening problem.
• Pregnancy extends it dramatically, up to 15 hours in the third trimester, which is part of why the recommended limit drops to 200 mg a day.
• Smoking cuts it almost in half. Quitting smoking makes your normal coffee habit suddenly cost you sleep, and this catches people out badly in the first weeks.
• Age has less effect than most people assume. A healthy 70 year old clears caffeine at close to the same rate as a 30 year old.

What to change first

Move the biggest cup, not the last one. Dropping the 4 pm espresso while keeping a 1 pm cold brew barely helps. The cold brew is four times the dose.

Count what you do not think of as coffee. A Diet Coke at 42 mg, a strong tea at 60 mg, a bar of dark chocolate at 40 mg, a pre-workout at 200 mg. The pre-workout before evening training is the single most common hidden cause of caffeine insomnia.

Set the cutoff by your bedtime, not by the clock. If you go to bed at 1 am, a 5 pm coffee is genuinely fine. Fixed advice about 2 pm assumes a schedule you may not keep.

Switch, do not just stop. Most people miss the hot drink more than the stimulant. Herbal tea is the only genuinely caffeine-free option, and decaf at 3 mg a cup is close enough that four in an evening still land under 12 mg.

What happens if you get it wrong

You will probably still fall asleep. Caffeine's effect on sleep onset is modest at moderate doses, which is why so many people conclude coffee does not affect them.

The damage shows up in the shape of the night. In one controlled study, 400 mg taken six hours before bed cut total sleep time by more than an hour, and the sleepers did not notice. Deep slow-wave sleep is the part that goes first, so you get the hours without the recovery, wake up flat, and reach for a coffee earlier the next morning. That is the loop worth breaking, and it closes on its own once the last cup moves a few hours earlier.