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Nights 1 to 3 · Lesson 4 of 11

Find Your Caffeine Cut-Off for Better Sleep

Learn how long caffeine stays in your body and how to pick a cut-off time for your last tea, coffee or cola.

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THE WRITTEN LESSONFollow along at your pace

Coffee helps many of us through the day. In this lesson you learn how long caffeine stays in your body, and how to pick your own cut-off time. This is general information, not medical advice.

Caffeine fades by halves

Caffeine does not disappear all at once. It fades by halves. In adults, half of it is gone after about three to seven hours. So after a coffee at 3 p.m., about half may still be in your body in the early evening, and about a quarter after midnight.

Three coffee cups along a day, from a sun to a moon. At 3 pm the cup is full, in the early evening it is about half full, and after midnight it is a quarter full. A label says Half-life: about 3 to 7 hours.(opens the full-size picture)
Full at 3 pm, half in the evening, a quarter after midnight.

What it does to sleep

Caffeine blocks a signal that builds up during the day and makes you sleepy. In a review of studies, caffeine taken mostly in the last few hours before bed cut sleep by about 45 minutes on average. Bigger doses closer to bedtime cut more.

Two bars under the heading Hours asleep. The tall navy bar is Usual sleep. The shorter red bar is With caffeine, with a coffee cup on the missing part and the words About 45 min less. A label says Bigger doses near bed cut more.(opens the full-size picture)
About 45 minutes less sleep on average in that review.

Falling asleep is not the test

Even if you fall asleep easily, caffeine can still add time awake in the night, and swap some deep sleep for lighter sleep. So “I fall asleep fine” does not mean coffee is not affecting you.

A card with the crossed-out line I fall asleep fine, so coffee doesn't affect me, and the correction It can still add wake time and cut deep sleep. Below, a usual night has two long Deep blocks. A night with caffeine has shorter Deep blocks and two yellow Awake blocks.(opens the full-size picture)
Same night, with more waking and less deep sleep.

Your cut-off

So when should you stop? The UK’s NHS says no tea or coffee in the six hours before bed. One review’s model suggests finishing an ordinary cup about nine hours before bed. For a ten o’clock bedtime, that is about one in the afternoon. Treat these as two ends of a range to try.

A day timeline from 1 pm to a 10 pm bedtime with a bed and moon at the end. A label says NHS: no tea or coffee after 4 pm, and a highlighted label says Model: last cup about 1 pm. A bracket shows About 9 hours before bed.(opens the full-size picture)
For a 10 pm bedtime: 4 pm by NHS advice, 1 pm by the model.

Count every source

Count every source, not just coffee. Tea, cola, chocolate, energy drinks, and some pain relievers and cold medicines contain caffeine. Even decaf has a little. Check the label on any medicine, or ask a pharmacist.

Five drawings in a row labelled Tea, Cola, Chocolate, Energy drinks, and Pain and cold medicines. Below them is a cup of decaf with a tag that says still has a little.(opens the full-size picture)
Caffeine hides in more places than coffee.

People differ

People differ a lot. Some clear caffeine faster, and others much more slowly, for example during pregnancy. Start with the earliest cut-off for your drink and bedtime, then adjust by how you sleep. If you are pregnant or take regular medicines, ask your doctor or pharmacist what is right for you.

Two figures. One is labelled Clears it faster with a short bar, Gone sooner. The other is labelled Clears it slower with a long bar, Stays in the body longer. Two labels read For example, during pregnancy and Start early, then adjust.(opens the full-size picture)
Same cup, different speeds.

YOUR TURN

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Read the full lesson script

Coffee helps many of us through the day. In this lesson, you'll learn how long caffeine stays in your body, and how to pick your own cut-off time.

Caffeine doesn't disappear all at once. It fades by halves. In adults, half of it is gone after about three to seven hours. So after a coffee at 3 p.m., about half may still be in your body in the early evening, and about a quarter after midnight.

Caffeine blocks a signal that builds up during the day and makes you sleepy. In a review of studies, caffeine taken mostly in the last few hours before bed cut sleep by about 45 minutes on average. Bigger doses closer to bedtime cut more.

Even if you fall asleep easily, caffeine can still add time awake in the night, and swap some deep sleep for lighter sleep.

So when should you stop? The UK's NHS says no tea or coffee in the six hours before bed. One review's model suggests finishing an ordinary cup about nine hours before bed. For a ten o'clock bedtime, that's about one in the afternoon.

Count every source, not just coffee. Tea, cola, chocolate, energy drinks, and some pain relievers and cold medicines contain caffeine. Even decaf has a little.

People differ a lot. Some clear caffeine faster, and others much more slowly, for example during pregnancy. Start with the earliest cut-off for your drink and bedtime, then adjust by how you sleep.

So remember: caffeine fades by halves, and it can cut deep sleep even when you fall asleep fine. Pick a cut-off six to nine hours before bed, and count every source. Before the next lesson, pick your cut-off time, and move your last cup before it. In the next lesson, you'll look at alcohol, late meals and evening exercise.