We all know caffeine can keep us awake, and there are obvious times to avoid it, like just before bed. So how late is too late to drink that afternoon coffee, or for how long does caffeine stay in your body?

Well, the key to this answer is the half-life of caffeine. Scientists use a phrase called "half-life" to describe how long it takes for the starting amount of a substance to be reduced by half in order to describe how long a stimulant like caffeine lasts in your body.

What is the half-life of caffeine?

According to the American Academy of Sleep Medicine, caffeine's half-life is between three and five hours.

As a result, you can keep feeling alert for up to five hours after consuming a caffeinated beverage since half of the caffeine is still in your system.

How long does caffeine stay in your system?

As an example, let’s say you drank an 8oz cup of coffee at breakfast (which has about 96 mg of caffeine), you would have roughly 48 mg of caffeine left in your system by midday.  And as long as there is little caffeine in your body, you can still experience its effects.

So, the caffeine will completely leave your system in approximately 10 hours.

Therefore, if you consumed one cup of coffee at 8am., the caffeine may still be present in your body until 6pm.

IMPORTANT: This information is intended to support, not replace, discussion with your doctor or healthcare professionals. Nothing in the content or products should be considered, or used as a substitute for, medical advice, diagnosis or treatment. You should always talk to your health care provider for diagnosis and treatment, including your specific medical needs.

November 14, 2022 — Guy Wilmot

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