Guides

For a mug of filter coffee and an 11 pm bedtime, about half past three. Here is how to work out your own cutoff from the cup you actually drink.

Caffeine peaks 45 minutes after you drink it, halves every 5.7 hours, and is effectively gone in about a day. What that means hour by hour.

About 5 to 6 hours for a healthy adult, 1.5 to 9.5 from person to person, up to 15 in pregnancy. The formula, the table and what changes it.

400 mg is the healthy adult limit, 200 mg in pregnancy, 200 mg in one sitting. What those numbers look like in real drinks.

Per millilitre espresso wins by five to one. Per cup filter coffee wins by half. Both facts are true and the cup is the one that matters.

Almost certainly yes. Caffeine six hours before bed cuts deep sleep measurably in people who report sleeping normally.

You cannot flush caffeine out. The liver clears about half every 5 to 6 hours. What eases the jitters, how long to wait, and when to get help.

Caffeine withdrawal starts 12 to 24 hours after the last cup, peaks on day one or two and lasts 2 to 9 days. The symptoms, day by day, and what eases them.

Caffeine raises anxiety in healthy people, most clearly above 400 mg a day. In panic disorder, 480 mg set off a panic attack in half of patients.

Up to 200 mg of caffeine a day is considered safe in pregnancy, about two mugs of coffee. What that looks like in real drinks, and why caffeine lasts longer.

Drink a coffee, then sleep for 15 to 20 minutes. In driving tests the pair cut errors to 9 percent of normal. How to time a coffee nap, and what it costs.

A Red Bull needs about six hours to clear, a Monster eleven and a half, a Celsius thirteen and a half. The cutoff times for every common can.

Yes, about 3 mg a cup instead of 96. Enough to matter in a few specific situations and nowhere near enough to keep you awake.

Cut by a quarter each week instead of stopping dead. The withdrawal headache is avoidable, and most people only need to cut back rather than quit.