Wellness

Caffeine and Sleep: When Should You Have Your Last Coffee?

September 30, 2026 · 4 min read · Sleep & Recovery

Cup of coffee on a saucer with coffee beans

Coffee is one of life’s great pleasures — and a genuinely effective way to feel more alert. But the afternoon cup may be costing you more sleep than you realise. Here’s what one well-designed study found, and how to enjoy caffeine without sacrificing your nights.

The study

In 2013, Christopher Drake and colleagues at the Henry Ford Hospital Sleep Disorders and Research Center gave healthy adults 400 mg of caffeine — roughly 3–4 cups of brewed coffee, depending on strength — at three different times: at bedtime, 3 hours before bed, and 6 hours before bed. On another night, they took a placebo. Sleep was measured objectively at home with a monitoring device, alongside sleep diaries.

400 mgcaffeine dose tested

6 hbefore bed — still disrupted sleep

>1 hless total sleep, even at 6 hours

Drake et al., Journal of Clinical Sleep Medicine (2013)

The results

Caffeine taken at bedtime and 3 hours before bed significantly disrupted sleep.
Even caffeine taken 6 hours before bed reduced objectively measured total sleep by more than an hour.
Participants didn’t always notice the effect in their sleep diaries. Your sleep can be worse without you realising why.

The study was small — 12 healthy adults — and 400 mg is a large single dose. But it shows clearly that caffeine’s effects can last well into the evening.

Why it lasts so long

Caffeine has a half-life of several hours in most adults, meaning a large share of a mid-afternoon coffee can still be active at bedtime. People vary a lot: genetics, pregnancy, some medications and other factors can slow how quickly caffeine is cleared. If you’re sensitive, you’ll feel this more.

How much caffeine is in your drink?

Caffeine content varies widely by brand, bean, brewing method and serving size. The chart shows typical ranges.

Typical caffeine per serving

Pre-workout supplement150–300 mg

Brewed coffee, 240 ml80–120 mg

Energy drink, 250 ml75–85 mg

Espresso, single60–80 mg

Black tea, 240 ml40–50 mg

Cola, 330 ml30–40 mg

Green tea, 240 ml25–35 mg

Typical ranges; check labels where available. Coffee-shop servings are often much larger than 240 ml.

View as table

Item	mg
Pre-workout supplement	150–300
Brewed coffee, 240 ml	80–120
Energy drink, 250 ml	75–85
Espresso, single	60–80
Black tea, 240 ml	40–50
Cola, 330 ml	30–40
Green tea, 240 ml	25–35

Notice where pre-workout supplements sit: a single scoop can match or exceed several coffees. If you train after work, that scoop may be the biggest threat to your sleep.

Set your caffeine cut-off

A practical rule based on the study: finish your last caffeinated drink at least 6 hours before bed — and 8 hours if you’re sensitive or you notice poor sleep.

Usual bedtime	Last caffeine (6 h rule)	Sensitive (8 h rule)
10:00 p.m.	4:00 p.m.	2:00 p.m.
10:30 p.m.	4:30 p.m.	2:30 p.m.
11:00 p.m.	5:00 p.m.	3:00 p.m.
11:30 p.m.	5:30 p.m.	3:30 p.m.
Midnight	6:00 p.m.	4:00 p.m.

Run a one-week experiment

Not sure whether caffeine affects you? Test it:

Days 1–3: keep your normal routine. Note what time you have each caffeinated drink and rate your sleep from 1–5 each morning.
Days 4–7: set an 8-hour cut-off. Keep everything else the same.
Compare. Did you fall asleep faster? Wake less? Feel better in the morning?

Many people are surprised by the difference.

Keep the ritual, lose the caffeine

If you love the afternoon coffee break more than the caffeine itself:

Switch to decaf after your cut-off. (Decaf still contains a small amount of caffeine, but far less.)
Try herbal teas such as peppermint, rooibos or chamomile.
Use a caffeine-free pre-workout, or train without one, for evening sessions.
Watch hidden sources: cola, energy drinks, iced teas, dark chocolate and some painkillers.

Using caffeine well

Caffeine isn’t the enemy. Used well, it can improve alertness and training performance. Make the most of it by:

having it earlier in the day, when you need it most;
avoiding stacking multiple sources in one afternoon;
noticing whether you need more and more for the same effect — a sign your sleep may be the real problem.

FAQ

I can drink espresso after dinner and still fall asleep. Am I immune? Falling asleep isn’t the whole story. In the study, sleep was reduced even when participants didn’t notice it. You may be sleeping more lightly than you think.

Is tea better than coffee? Tea usually contains less caffeine per cup, so it’s easier to fit within a cut-off — but the timing rule still applies.

How much caffeine is too much in a day? Health authorities commonly cite up to about 400 mg a day as generally safe for most healthy adults. Lower limits apply during pregnancy and for some medical conditions — ask your doctor.

The bottom line

Caffeine is useful, but it lingers. Keep it to the first half of the day, set a cut-off at least 6 hours before bed, and you’ll protect the 7+ hours of sleep that experts recommend.

Sources

Drake C et al. (2013). Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine. doi:10.5664/jcsm.3170
Watson NF et al. (2015). Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. SLEEP. doi:10.5665/sleep.4716

This article is general education for healthy adults, not medical advice. Check with a qualified professional before starting a new exercise or nutrition plan, especially if you have a medical condition. Full disclaimer.