How Long Does Caffeine Last?
Caffeine's half-life averages about 5 hours, so half a dose is still in you hours later. What makes it last longer, and when to stop before bed.
Recovery & Caffeine
Rest, sleep and caffeine: what the evidence and health agencies say.
Guides
How Much Caffeine Is Too Much?
Most healthy adults can have up to 400 mg of caffeine a day. See the lower limits for pregnancy and kids, signs of too much, and caffeine in common drinks.