Caffeine cutoff

Have your last coffee at least 9 hours before bed. Caffeine cuts sleep and deep sleep even when you fall asleep fine.

• Evidence: Strong
• Low effort
• Free
• Works: tonight

Why it matters

Caffeine keeps you alert by blocking adenosine, one of the signals of sleep pressure. It doesn’t remove the pressure; it hides it for as long as caffeine is in your blood.

A meta-analysis of 24 studies found that caffeine cut total sleep by an average of 45 minutes and sleep efficiency by 7%. People took 9 minutes longer to fall asleep, spent 12 more minutes awake during the night, and got about 11 minutes less deep sleep [1].

Caffeine also lasts longer than most people think. Its average half-life in healthy adults is about 5 hours, meaning half is still in your blood 5 hours later. But it ranges from 1.5 to 9.5 hours between people [5]. Much of the difference comes from one liver enzyme, CYP1A2, which breaks down about 95% of caffeine. Its activity is affected by your genes, age, sex and hormones, liver disease, smoking, diet and some medications [7].

How to do it

1. Find your cutoff. Take your usual bedtime and subtract 9 hours for coffee or tea, or 13 hours for an energy drink or pre-workout. The meta-analysis found that a 250 mL (8.5 fl oz) coffee with 107 mg of caffeine needs at least 8.8 hours, and a 217.5 mg pre-workout at least 13.2 hours, to avoid losing sleep [1].

2. Count every source. The FDA gives these ranges for a 12 fl oz (355 mL) serving [6]:

   Drink, 12 fl oz (355 mL)	Caffeine
   Brewed coffee	113–247 mg
   Energy drink	41–246 mg
   Black tea	71 mg
   Caffeinated soft drink	23–83 mg

3. Stay under 400 mg a day. The FDA says that amount isn’t generally linked to harmful effects in healthy adults [6]. That’s a safety limit, not a sleep target.

4. Move your afternoon coffee to the morning, or switch it to decaf.

5. If you sleep badly anyway, try an earlier cutoff. Some people are much more sensitive than average [3].

Pregnant, or taking medication? Ask your doctor or pharmacist what’s right for you; caffeine interacts with many medicines [7].

Common mistakes

• “I can drink espresso after dinner and sleep fine.” You may fall asleep, but caffeine typically reduces deep sleep and increases light sleep and wake-ups [3].
• Thinking 6 hours is plenty. In a small trial, 400 mg taken 6 hours before bed cut measured sleep by more than an hour. People underestimated the loss in their own sleep diaries [2].
• Forgetting pre-workout. A typical serving needs about 13 hours to clear enough [1]. If you train in the evening, use a caffeine-free pre-workout or none; liftgood.now has evening training advice.
• Assuming the morning cup can’t matter. In 9 men, 200 mg at 7 a.m. still reduced sleep time and efficiency that night [4]. That’s a small study, but if you sleep badly, cut down overall too.

Effect on your sleep score

• Total sleep, efficiency, time to fall asleep and wake-ups: all get worse with caffeine, by the average amounts above [1]. These are averages across many doses and timings. A late large dose costs more than an early small one.
• Deep sleep: about 11 minutes less on average [1], and early-night deep sleep is where it shows.
• Resting heart rate: Oura lists caffeine among things that can raise your overnight resting heart rate [8]. That’s the company’s guidance; we didn’t find a study measuring it in wearable users.
• HRV: we found no good evidence either way.

How confident: high for sleep time, efficiency and deep sleep; low for heart rate and HRV.

Evidence

Rated Strong. A 2023 meta-analysis of 24 studies [1] and a systematic review of trials and observational studies [3] agree: caffeine delays sleep, shortens it and makes it lighter, and the effect depends on dose and timing.

Limits: most studies were in Western adult men [3]. The cutoff times are averages; your own half-life could be much shorter or longer [5]. Many trials used single doses, not daily coffee habits.

General information for healthy adults, not medical advice. If you have a sleep problem that lasts, read when to see a doctor. Sources checked 4 October 2026. Spot a mistake? Tell us.