How Long Does Caffeine Stay in Your Bloodstream?

According to the American Academy of Sleep Medicine, caffeine reaches a peak level in the bloodstream within 30 to 60 minutes. It has a half-life of three to five hours, meaning it takes that amount of time to remove half the caffeine from the system.

The American Academy of Sleep Medicine states that after half the caffeine is removed from the body, the remaining caffeine can stay in the body for eight to 14 hours. Caffeine is a stimulant; it blocks the body's receptors for adenosine, a substance which promotes sleepiness, thereby keeping the body from feeling sleepy.