How many hours before bed should I stop drinking caffeine?

For a typical cup of coffee, stop about 6 hours before bed. Larger doses need more time: a 200 mg drink needs about 12 hours with an average 6-hour half-life. A lab study found that even 400 mg taken 6 hours before bed cut sleep by over an hour.

How long does caffeine stay in your system?

Caffeine has an average half-life of 5 to 7 hours, so half the dose is still in your body after that time. After about 10 to 12 hours a single cup is mostly cleared, but genetics, pregnancy, oral contraceptives and smoking can speed it up or slow it down.

Does caffeine affect melatonin?

Yes. Caffeine blocks adenosine and can delay your body clock: one study found caffeine taken 3 hours before bed delayed melatonin onset by about 40 minutes. Natural melatonin starts rising about 2 hours before sleep, so stopping caffeine and dimming lights before then protects it.

Does decaf coffee have caffeine?

Yes, a small amount. An 8 oz cup of decaf usually has about 2 to 7 mg, which is far below the 50 mg threshold used here, so it is fine for most people in the evening.

Can I take melatonin and caffeine on the same day?

Generally yes, as long as the caffeine ends by your cut-off time. Melatonin supplements are usually taken around 30 to 60 minutes before bed, so caffeine in the afternoon will not overlap. Speak to a doctor or pharmacist before taking melatonin regularly.

Caffeine Cut-Off Calculator: Safe Drink Time

Caffeine & Melatonin Cut-Off Calculator

Save on Google

Find the last time you can drink caffeine without hurting tonight's sleep. Enter your bedtime, your drink or dose in milligrams, and how fast you clear caffeine to get your cut-off deadline, the caffeine left at bedtime and your natural melatonin window. Everything is calculated privately in your browser.

← Want your full bedtime plan? Use our Complete Sleep Calculator & Bedtime Matrix

Target bedtime

Beverage or supplement

Caffeine dose (mg)

How fast do you clear caffeine?

Deadline

Safe caffeine cut-off

Residual

Caffeine left at bedtime

Melatonin

Natural melatonin onset

Wind-Down

Screens-down curfew

The cut-off is the time when the remaining caffeine falls to about 50 mg, using a simple half-life model. Caffeine peaks 30 to 60 minutes after drinking. Keep total daily caffeine under 400 mg for healthy adults.

How Caffeine Works in Your Body

Caffeine is absorbed within 30 to 60 minutes and reaches peak levels in your blood about an hour after you drink it. It blocks adenosine receptors in the brain, so the sleep pressure that builds up all day stops registering. The caffeine does not make you less tired, it only hides the tiredness, which is why the effect ends in a crash and why late doses make it harder to fall asleep.

Half-Life and the Cut-Off Formula

The liver clears caffeine at a steady proportion, so the amount left follows a half-life curve. The average half-life is 5 to 7 hours, which means half the dose is still active after that time. This calculator uses 5 hours for fast metabolizers, 6 hours for average and 7 hours for slow metabolizers. The cut-off is the time at which the remaining caffeine drops to about 50 mg, a level that is unlikely to disturb sleep for most people. The formula is: hours before bed = half-life × log2(dose ÷ 50).

Your personal half-life can be different. Oral contraceptives can roughly double it, pregnancy lengthens it further, and smoking shortens it. If you often lie awake after afternoon coffee, choose slow metabolizer.

Caffeine and the Melatonin Window

Melatonin is the hormone that signals night. Under dim light it starts rising about 2 hours before your usual bedtime. Bright screens suppress it, and caffeine can delay it: one study found that caffeine taken 3 hours before bed delayed the body clock by about 40 minutes. Protecting the window means dimming lights and finishing caffeine before it opens. If you use melatonin supplements, they are usually taken 30 to 60 minutes before bed, and you should talk to a doctor first.

Step-by-Step Examples

200 mg Cold Brew, Bedtime 11:00 PM

Enter 200 mg and 11:00 PM with an average metabolizer. Your cut-off is 11:00 AM, 12 hours before bed, and 200 mg has fallen to 50 mg by then. A fast metabolizer can push this to 1:00 PM, and a slow one needs 9:00 AM.

Double Espresso Before a 10:30 PM Bedtime

Choose the double espresso at 126 mg with an average metabolizer. The cut-off is 2:25 PM, about 8 hours before bed, because 126 mg needs about 1.3 half-lives to fall to 50 mg. Use the tool to see the exact time for your own bedtime.

Energy Drink and a Midnight Bedtime

Choose a 160 mg energy drink, a midnight bedtime and slow metabolizer. The calculator gives a cut-off of 12:15 PM, almost 12 hours before bed. A second can at 6:00 PM would still leave about 90 mg in your system at midnight.

Beverage and Supplement Caffeine vs Required Clearance Hours

Forty common drinks and supplements with typical caffeine content and the hours needed to fall to 50 mg. The last column assumes an 11:00 PM bedtime and an average metabolizer. Caffeine content varies by brand and preparation, so check the label when you can.

Beverage and supplement caffeine content versus required clearance hours (time to fall to 50 mg)
Beverage / Supplement	Serving Size	Caffeine	Clearance: Fast (5h)	Clearance: Average (6h)	Clearance: Slow (7h)	Latest Drink for 11 PM Bed (Average)
Espresso, single shot	1 oz (30 ml)	63 mg	1.7 h	2.0 h	2.3 h	8:55 PM
Espresso, double shot	2 oz (60 ml)	126 mg	6.7 h	8.0 h	9.3 h	2:55 PM
Latte or cappuccino (1 shot)	12 oz	63 mg	1.7 h	2.0 h	2.3 h	8:55 PM
Instant coffee	8 oz	62 mg	1.6 h	1.9 h	2.2 h	9:05 PM
Drip coffee	8 oz	95 mg	4.6 h	5.6 h	6.5 h	5:25 PM
Drip coffee	12 oz	140 mg	7.4 h	8.9 h	10.4 h	2:05 PM
Drip coffee	16 oz	190 mg	9.6 h	11.6 h	13.5 h	11:25 AM
Cold brew	12 oz	155 mg	8.2 h	9.8 h	11.4 h	1:10 PM
Cold brew	16 oz	205 mg	10.2 h	12.2 h	14.2 h	10:45 AM
Cold brew	20 oz	310 mg	13.2 h	15.8 h	18.4 h	7:10 AM
Decaf coffee	8 oz	3 mg	0.0 h	0.0 h	0.0 h	Any time before bed
Black tea	8 oz	47 mg	0.0 h	0.0 h	0.0 h	Any time before bed
Oolong tea	8 oz	38 mg	0.0 h	0.0 h	0.0 h	Any time before bed
Green tea	8 oz	28 mg	0.0 h	0.0 h	0.0 h	Any time before bed
White tea	8 oz	20 mg	0.0 h	0.0 h	0.0 h	Any time before bed
Matcha	8 oz (about 2 g powder)	70 mg	2.4 h	2.9 h	3.4 h	8:05 PM
Yerba mate	8 oz	85 mg	3.8 h	4.6 h	5.4 h	6:20 PM
Chai latte	12 oz	60 mg	1.3 h	1.6 h	1.8 h	9:25 PM
Bottled iced tea	16 oz	40 mg	0.0 h	0.0 h	0.0 h	Any time before bed
Kombucha	8 oz	15 mg	0.0 h	0.0 h	0.0 h	Any time before bed
Cola	12 oz can	34 mg	0.0 h	0.0 h	0.0 h	Any time before bed
Diet cola	12 oz can	46 mg	0.0 h	0.0 h	0.0 h	Any time before bed
Dr Pepper	12 oz can	41 mg	0.0 h	0.0 h	0.0 h	Any time before bed
Mountain Dew	12 oz can	54 mg	0.6 h	0.7 h	0.8 h	10:20 PM
Red Bull	8.4 oz can	80 mg	3.4 h	4.1 h	4.7 h	6:55 PM
Red Bull	12 oz can	114 mg	5.9 h	7.1 h	8.3 h	3:50 PM
Monster	16 oz can	160 mg	8.4 h	10.1 h	11.7 h	12:55 PM
Rockstar	16 oz can	160 mg	8.4 h	10.1 h	11.7 h	12:55 PM
Celsius	12 oz can	200 mg	10.0 h	12.0 h	14.0 h	11:00 AM
High-caffeine energy drink	16 oz can	300 mg	12.9 h	15.5 h	18.1 h	7:25 AM
Energy shot	2 oz bottle	200 mg	10.0 h	12.0 h	14.0 h	11:00 AM
Caffeine pill	100 mg tablet	100 mg	5.0 h	6.0 h	7.0 h	5:00 PM
Caffeine pill	200 mg tablet	200 mg	10.0 h	12.0 h	14.0 h	11:00 AM
Pre-workout (moderate)	1 scoop	200 mg	10.0 h	12.0 h	14.0 h	11:00 AM
Pre-workout (high-stimulant)	1 scoop	300 mg	12.9 h	15.5 h	18.1 h	7:25 AM
Headache tablets with caffeine	2 tablets	130 mg	6.9 h	8.3 h	9.6 h	2:40 PM
Caffeine gum	1 piece	50 mg	0.0 h	0.0 h	0.0 h	Any time before bed
Dark chocolate (70-85%)	1 oz bar	23 mg	0.0 h	0.0 h	0.0 h	Any time before bed
Milk chocolate bar	1.5 oz	10 mg	0.0 h	0.0 h	0.0 h	Any time before bed
Hot cocoa	8 oz	5 mg	0.0 h	0.0 h	0.0 h	Any time before bed

Hourly Adenosine Receptor Clearance Timeline

The percentage of caffeine remaining at each hour after you drink it for each metabolizer type, plus the milligrams left from a 200 mg dose.

Hourly adenosine receptor clearance timeline (percent of caffeine remaining)
Time After Drinking	Remaining: Fast (5h)	Remaining: Average (6h)	Remaining: Slow (7h)	From a 200 mg Dose (Average)	Adenosine Receptor Effect	Sleep Impact
1 h	87%	89%	91%	178 mg	Peak blood levels; receptors strongly blocked	Alertness at its highest
2 h	76%	79%	82%	159 mg	Strong block continues	Still far too soon for any bedtime
4 h	57%	63%	67%	126 mg	Moderate to strong block	Falling asleep is still likely to be delayed
6 h	44%	50%	55%	100 mg	Moderate block; roughly half remains	Drake et al. (2013): 400 mg taken 6 h before bed cut sleep by over an hour
8 h	33%	40%	45%	79 mg	Mild to moderate block	Lighter, less deep sleep is still possible
10 h	25%	31%	37%	63 mg	Mild block	Small effect for most people with a normal serving
12 h	19%	25%	30%	50 mg	Low residual block	Usually fine after a single standard serving
16 h	11%	16%	21%	31 mg	Trace amounts	No meaningful effect on tonight's sleep
24 h	4%	6%	9%	13 mg	Mostly cleared	Cleared before the next day's first dose

Melatonin Suppression Risk by Screen Light and Evening Stimulants

Risk levels are approximate and depend on brightness, distance and how long you are exposed. Use them as a guide for your evening routine.

Melatonin suppression risk by screen light and evening stimulants (approximate)
Evening Exposure	Typical Intensity	Melatonin Suppression Risk	Approximate Effect	Curfew Before Bed	Mitigation
Bright overhead room light	Over 200 lux	High	Clear suppression and later melatonin onset	2 hours before bed	Switch to warm lamps under 30 lux
Phone or tablet at full brightness	Blue-rich, held close to the eyes	High	Suppresses melatonin and delays sleep onset	2 hours before bed	Lower brightness, hold it farther away, use night mode
Backlit e-reader or tablet reading	Blue-rich, sustained use	High	Chang et al. (2015): melatonin onset delayed by roughly 1.5 h	1–2 hours before bed	Read a paper book or use an e-ink reader
Laptop or TV	Moderate brightness, farther away	Moderate	Smaller delay that grows with brightness and time	1 hour before bed	Turn on night mode and dim the room
Night mode and low brightness	Warm, dimmed screen	Low to moderate	Reduces but does not remove the effect	30–60 minutes before bed	Pair with room lights turned down
Dim warm lamps	Under 30 lux	Low	Little effect on melatonin	Fine up to bedtime	Use amber bulbs in bedroom and bathroom
Blue-blocking glasses	Amber lenses	Low	Can limit the blue-light effect of screens	Wear 2 hours before bed	Combine with dimmer screens
Caffeine within 6 hours	Over 50 mg remaining	Moderate	Burke et al. (2015): caffeine 3 h before bed delayed the body clock by about 40 min	Use your cut-off time	Stop caffeine at the calculated deadline
Caffeine plus bright screens	Both stimulants together	High	Effects stack: later onset and lighter sleep	Cut-off time and 2 hours of dim light	Drop both in the evening
Nicotine	Stimulant, shorter half-life	Moderate	Raises arousal and fragments sleep	At least 2 hours before bed	Avoid late-evening use

Frequently Asked Questions

People also ask: caffeine and sleep FAQ
Question	Answer
How many hours before bed should I stop drinking caffeine?	For a typical cup of coffee, stop about 6 hours before bed. Larger doses need more time: a 200 mg drink needs about 12 hours with an average 6-hour half-life. A lab study found that even 400 mg taken 6 hours before bed cut sleep by over an hour.
How long does caffeine stay in your system?	Caffeine has an average half-life of 5 to 7 hours, so half the dose is still in your body after that time. After about 10 to 12 hours a single cup is mostly cleared, but genetics, pregnancy, oral contraceptives and smoking can speed it up or slow it down.
Does caffeine affect melatonin?	Yes. Caffeine blocks adenosine and can delay your body clock: one study found caffeine taken 3 hours before bed delayed melatonin onset by about 40 minutes. Natural melatonin starts rising about 2 hours before sleep, so stopping caffeine and dimming lights before then protects it.
Does decaf coffee have caffeine?	Yes, a small amount. An 8 oz cup of decaf usually has about 2 to 7 mg, which is far below the 50 mg threshold used here, so it is fine for most people in the evening.
Can I take melatonin and caffeine on the same day?	Generally yes, as long as the caffeine ends by your cut-off time. Melatonin supplements are usually taken around 30 to 60 minutes before bed, so caffeine in the afternoon will not overlap. Speak to a doctor or pharmacist before taking melatonin regularly.

Medical disclaimer: This calculator is an educational tool and not medical advice. Caffeine is not suitable for everyone, including people who are pregnant, have heart rhythm problems, anxiety or high blood pressure, so ask a doctor first. If you cannot sleep despite stopping caffeine early, speak to a doctor about insomnia or another sleep disorder.