When you drink coffee or energy drinks, the caffeine half-life, the time it takes for your body to eliminate half the caffeine you consumed. Also known as caffeine metabolism rate, it determines how long you feel alert — or how long you can't sleep. For most people, that half-life is about 5 hours, but it can range from 3 to 7 hours depending on your genes, liver health, and what else you're taking.
That number isn’t just trivia. If you're on blood pressure meds, antidepressants, or even birth control pills, caffeine can stick around longer and mess with how those drugs work. People who take oral contraceptives, for example, may see their caffeine half-life double. Smokers? They clear caffeine faster. Pregnant women? It can stretch to 10+ hours. This isn’t about cutting coffee — it’s about understanding how your body handles it. The same way licorice root can cancel out blood pressure meds, caffeine can quietly interfere with your meds without you noticing.
And it’s not just about sleep. If you’re feeling jittery, anxious, or your heart races after a cup of coffee, it might not be the amount — it’s the timing. Caffeine lingers in your system long after you feel its effects. That’s why people who drink coffee at 3 p.m. still can’t fall asleep at night. Your body doesn’t know when to turn it off. That’s where knowing your personal caffeine half-life helps. You don’t need to quit caffeine. You just need to know when to stop.
What you’ll find below are real, practical posts that connect caffeine’s behavior in your body to other medications, health conditions, and daily habits. From how it interacts with antidepressants to why some people feel wired for hours and others crash fast — this collection gives you the facts you need to make smarter choices, not guesswork.
