How Long Does Caffeine Last? Half-Life, Peak and Sleep

Caffeine is almost fully absorbed within 45 minutes, peaks in the blood between 15 minutes and 2 hours, and has an average half-life of about 5 hours, so half of a morning coffee is still in your body at lunch. The half-life ranges from 1.5 to 9.5 hours between people (Institute of Medicine), which is why some people can sleep after an evening espresso and others cannot. In sleep studies, 400 mg of caffeine taken 6 hours before bed still disturbed sleep (Drake et al., 2013). This guide covers the timeline, what makes caffeine last longer, and when to stop for the day.

It is educational, not medical advice.

Key Takeaways

• Fast in: 99% of caffeine is absorbed within 45 minutes, and blood levels peak 15 to 120 minutes after you swallow it (Institute of Medicine).
• Slow out: the average half-life is about 5 hours, with a range of 1.5 to 9.5 hours (Institute of Medicine).
• Some people clear it slower: oral contraceptives can double the half-life, smoking speeds caffeine breakdown, and pregnancy changes clearance (Institute of Medicine).
• Sleep cutoff: a review of 24 studies found that a cup of coffee (107 mg) should be finished at least 8.8 hours before bed to avoid losing sleep, and a 217.5 mg pre-workout at least 13.2 hours before (Gardiner et al., 2023).
• Daily limit: the FDA cites 400 mg a day as an amount not generally associated with negative effects for most adults (FDA).

How Long Does Caffeine Last? The Timeline

Caffeine is rapidly and completely absorbed: 99% is absorbed within 45 minutes of drinking it, and blood levels peak somewhere between 15 and 120 minutes later. The spread depends on how quickly your stomach empties and on what else you have eaten (Institute of Medicine). After the peak, your liver clears it slowly. The average half-life in healthy adults is about 5 hours (Institute of Medicine), which means the amount in your blood halves roughly every 5 hours.

Time after a 200 mg coffee	Caffeine left (average 5 hour half-life)
Within 45 minutes	Almost all absorbed
15 to 120 minutes	Peak blood level
5 hours	About 100 mg
10 hours	About 50 mg
15 hours	About 25 mg

These numbers are for an average half-life (Institute of Medicine). If your half-life is closer to 9 hours, a 200 mg morning coffee still leaves about 100 mg in your blood in the late afternoon. The amount in each drink varies too; see the table further down. Our guide to how to stay awake covers using caffeine well when you need it.

Caffeine Half-Life by the Clock: One Morning Coffee

Half-life is the time it takes for the caffeine in your blood to drop by half. The average is about 5 hours, with a range of 1.5 to 9.5 hours (Institute of Medicine). Here is what that average looks like for a 200 mg coffee at 8 AM.

Time	What is happening	Caffeine left (average 5 hour half-life)
8:00 AM	You finish a 200 mg coffee	200 mg on board
By 8:45 AM	Almost all of it is absorbed	Close to 200 mg
8:15 to 10:00 AM	Peak blood level	Highest point of the day
1:00 PM	One half-life	About 100 mg
6:00 PM	Two half-lives	About 50 mg
11:00 PM	Three half-lives	About 25 mg

If your half-life is closer to 9 hours, that 100 mg point moves to the late afternoon. A double espresso adds up the same way; see how much caffeine is in espresso. If late caffeine has already pushed your bedtime back, our guide on how to fix your sleep schedule walks through a reset. Our caffeine-free Theanine Nasal Spray, 36 mg of L-theanine per serving, is designed to pair with your morning coffee or tea, so it fits a front-loaded caffeine day. If you also take NAD+ in the morning, our guide to NAD+ and caffeine covers how to time the two.

Why Caffeine Lasts Longer for Some People

The 1.5 to 9.5 hour range comes from both inborn differences and things that change how fast the liver breaks caffeine down (Institute of Medicine). The FDA also notes wide variation in how sensitive people are to caffeine and how fast they clear it (FDA).

• Oral contraceptives: can double the half-life of caffeine (Institute of Medicine).
• Pregnancy: changes how quickly caffeine is cleared (Institute of Medicine). If you are pregnant, trying to become pregnant or breastfeeding, the FDA recommends talking to your provider about whether to limit caffeine (FDA).
• Smoking: speeds up caffeine breakdown, and stopping smoking returns clearance to nonsmoking levels (Institute of Medicine), so people who quit can find their usual coffee hits harder.
• Your genes and body: individual variation is a large part of the spread (Institute of Medicine).

How Long Before Bed Should You Stop Caffeine?

In a study that gave 400 mg of caffeine at bedtime, 3 hours before bed or 6 hours before bed, all three timings disturbed sleep compared with placebo. The authors concluded that caffeine taken 6 hours before bedtime still has important disruptive effects and supported avoiding substantial caffeine for at least 6 hours before bed (Drake et al., 2013).

A 2023 systematic review of 24 studies put numbers on the effect. Caffeine cut total sleep time by 45 minutes and sleep efficiency by 7%, added 9 minutes to the time it took to fall asleep and 12 minutes of waking during the night, and reduced deep sleep by about 11 minutes. To avoid losing sleep time, the authors calculated that a cup of coffee (107 mg per 250 mL) should be drunk at least 8.8 hours before bed, and a standard pre-workout (217.5 mg) at least 13.2 hours before (Gardiner et al., 2023).

Bedtime	Last cup of coffee (8.8 hours before)
10 PM	About 1 PM
11 PM	About 2 PM
Midnight	About 3 PM

Our guide to how to sleep better has more on building a routine around an earlier cutoff.

Caffeine and Melatonin

Caffeine also shifts the body clock. In a 49 day study, a caffeine dose equal to a double espresso taken 3 hours before bed delayed the evening rise of melatonin by about 40 minutes, nearly half the delay caused by 3 hours of bright evening light (Burke et al., 2015). So a late coffee can push your natural sleep signal later, on top of keeping you alert.

For daily limits and the signs you have had too much, see how much caffeine is too much.

How Much Caffeine Is in Your Drink?

Drink	Caffeine (FDA ranges)
Brewed coffee, 12 fl oz	113 to 247 mg
Decaf coffee, 8 fl oz	2 to 15 mg
Caffeinated soft drink, 12 fl oz	23 to 83 mg
Energy drink, 16 fl oz	54 to 328 mg

Source: (FDA). The FDA cites 400 mg a day as an amount not generally associated with negative effects for most adults, lists sleep problems among the signs of too much caffeine, and warns that pure and highly concentrated caffeine powders can be dangerous (FDA). Our list of coffee alternatives includes options with less or no caffeine, and our guide to theobromine vs caffeine compares the stimulant in cocoa.

Decaf and chocolate still add some caffeine; see how much caffeine is in decaf coffee and does chocolate have caffeine.

To plan your cups around the day, see the best time to drink coffee, and for how quickly coffee and tablets kick in, caffeine pills vs coffee.

How to Make Caffeine Work for You

1. Set a cutoff. Count back about 9 hours from bedtime for coffee, longer for strong pre-workouts (Gardiner et al., 2023).
2. Front-load your day. Have your caffeine in the morning so most of it is gone by evening.
3. Watch the hidden sources. Tea, soft drinks, energy drinks and some supplements add up.
4. Plan for the dip. Our guide to the caffeine crash explains why energy can drop as caffeine wears off.
5. Consider L-theanine with coffee. Our guide to L-theanine and caffeine covers the ratio and timing studies used.

If you plan to cut back, our guide to caffeine withdrawal covers the timeline.

Where Our Products Fit

Our Theanine Nasal Spray provides 36 mg of L-theanine per serving and is caffeine-free, designed to pair with your morning coffee or tea. The Energy Stack combines NAD+ Nasal Spray, Forage and Methyl B-12 Nasal Spray in one daily energy routine. Learn more on our L-theanine ingredient page and in our non-stimulant energy and focus hub. Talk to your doctor before starting a new product if you are pregnant, breastfeeding or take medication.

Frequently Asked Questions

How long does caffeine stay in your system?

The average half-life is about 5 hours, so half of a dose is gone in about 5 hours and three quarters in about 10, but it can range from 1.5 to 9.5 hours (Institute of Medicine).

How long does it take for caffeine to kick in?

Most of it is absorbed within 45 minutes, and blood levels peak 15 to 120 minutes after you drink it (Institute of Medicine).

What time should I stop drinking coffee?

A review of 24 studies suggests finishing a cup of coffee at least 8.8 hours before bed (Gardiner et al., 2023). For an 11 PM bedtime, that is about 2 PM.

Can caffeine 6 hours before bed affect sleep?

Yes. 400 mg taken 6 hours before bedtime still disturbed sleep compared with placebo (Drake et al., 2013).

Why does caffeine affect me more than other people?

Half-life varies with your genes and with factors such as oral contraceptives, pregnancy and smoking (Institute of Medicine).

Does caffeine affect melatonin?

Evening caffeine equal to a double espresso delayed the melatonin rhythm by about 40 minutes in one study (Burke et al., 2015).

How much caffeine is too much in a day?

The FDA cites 400 mg a day for most adults as an amount not generally associated with negative effects, and advises people who are pregnant or breastfeeding to ask their provider (FDA).

What is the half-life of caffeine?

About 5 hours on average in healthy adults, with a range of 1.5 to 9.5 hours between people (Institute of Medicine).

How long does a morning coffee last?

With an average half-life, a 200 mg coffee at 8 AM leaves about 100 mg at 1 PM, 50 mg at 6 PM and 25 mg at 11 PM (Institute of Medicine).

When should I stop caffeine if I take a pre-workout?

Earlier than coffee. A review of 24 studies found a standard pre-workout (217.5 mg) should be taken at least 13.2 hours before bed (Gardiner et al., 2023). For an 11 PM bedtime, that is before about 10 AM.

Sources

1. Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med. 2013. PubMed 24235903
2. Gardiner C, Weakley J, Burke LM, et al. The effect of caffeine on subsequent sleep: a systematic review and meta-analysis. Sleep Med Rev. 2023. PubMed 36870101
3. Burke TM, Markwald RR, McHill AW, et al. Effects of caffeine on the human circadian clock in vivo and in vitro. Sci Transl Med. 2015. PubMed 26378246
4. Institute of Medicine (US) Committee on Military Nutrition Research. Pharmacology of Caffeine. In: Caffeine for the Sustainment of Mental Task Performance. National Academies Press; 2001. Institute of Medicine
5. U.S. Food and Drug Administration. Spilling the Beans: How Much Caffeine Is Too Much? FDA

Our products are not intended to diagnose, treat, cure or prevent any disease. This article is for education only and is not medical advice.