Caffeine & Sleep
Soda

Caffeine in Diet Coke

46mg
per 12 oz
≈ 1 Red Bull12% of FDA daily max

Is that a lot?

Diet Coke is 12% of the FDA’s recommended daily maximum, in a single 12 oz.

Green tea
28 mg
Diet Coke
46 mg
Espresso
63 mg
Red Bull
80 mg
Coffee
95 mg
FDA daily max · 400mg
Before bed

When can I drink Diet Coke and still sleep?

Your Diet Coke cutoff
You drink it at
Bedtime
Diet Coke · 46 mg · assuming an average ~5 h half-life
At bedtime
15 mg
close to optimal
Latest safe Diet Coke: 11:00 PM

How much caffeine is in Diet Coke?

Diet Coke quietly out-caffeinates regular Coke, with about 46 mg in a 12 oz can versus Classic's 34. There's no sugar here, just a slightly firmer caffeine kick than its full-calorie sibling.

ServingCaffeineSugar
12 oz46 mg0 g

Higher caffeine than regular Coke.

Will Diet Coke affect your sleep?

From 46 mg, Diet Coke is just under the 50 mg threshold and falls further within an hour or so. An afternoon can is usually fine by bedtime, though several through the evening can add up.

Source: Manufacturer label

Related drinks

Diet Coke & sleep — FAQ

One can at 46 mg sits just below the 50 mg threshold, so it's unlikely to keep you up, but multiple cans late in the evening can stack toward a restless night.

Diet Coke has 46 mg per 12 oz — about 12% of the FDA’s 400 mg daily maximum for healthy adults.

It depends on your bedtime and how fast you clear caffeine. Use the calculator above to see when Diet Coke drops below the ~50 mg “ok to sleep” threshold for your bedtime.

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