Caffeine Has A Half-Life Of 5 Hours

On average.¹

Half-Life

The amount of time it takes for the quantity to drop by half. Since it’s always half of the current amount, that means half-life’s aren’t linear - it takes much longer for the final molecules to be removed than the earlier ones.

What’s the Latest I Should Drink Caffeine?

Well, that depends on how much you drank. Caffeine Removes The Tired, so you probably want to have most of it out of your system before going to bed.

Caffeine Amounts Lookup Table

5-Hour Energy shot | 200mg Monster Energy | 160mg Can of Coke | 50mg Bottle of Coke | 76mg See Caffeine chart for a more comprehensive list.

If you had a 16oz black coffee at 7am, that’s 310mg of caffeine. Halving every 5hrs, you’d still have 40mg in your system at 10pm.

If you feel like 10pm is too late to drink a can of coke, well, you already are.

Balancing Caffeine and Sleep is a numbers game.

You can drink less, or you can drink earlier. Either way, you’ll probably still have a bit it your system by the time you go to bed, since it takes progressively longer to clear out the smaller and smaller amounts.

See Also

• Caffeine chart | Center for Science in the Public Interest
• Pharmacology of Caffeine - Caffeine for the Sustainment of Mental Task Performance - NCBI Bookshelf

Footnotes

1. Actual rates can vary be between 1.5hrs and 9.5hrs. Let’s stick with 5 to keep the math easy. ↩