How long does a cup of coffee keep you up?


While everyone’s body is different and everyone has a slightly different response to coffee,for many of us the effects of coffee can be felt in minutes and keep us wired for quite some time.



Levels of caffeine (active ingredient in coffee responsible for its energizing effects) in our blood peak within 15-45 minutes but the effects last much longer. Caffeine has a half-life of approximately 5 hours.



When scientists determine how long something lasts, they call it a half-life. A half-life is the amount of time it takes for the compound or substance to decrease by half. This means that every 5 hours, half of the remaining caffeine is removed from our body and metabolized by our liver. As an example if you drink a cup at noon, by 5 pm about half will still be in your bloodstream. At 10 pm about 25% will still remain!



The American Academy of Sleep Medicine has listed the following estimates for caffeine content of common drinks:


  • 8 ounces (oz) of brewed coffee – 95 mg


  • 1 oz of espresso – 64 mg
  • 8 oz of brewed tea – 47 mg
  • 16-oz average energy drink – 158 mg (almost 3 espressos)
  • 12-oz average caffeinated soda – 45 mg
  • 1.55-oz milk chocolate candy bar – 9 mg



To reinforce what we spoke about above – 5 hours after drinking 8 ounces of coffee, you will still have 47.5 mg of caffeine circulating throughout your body (as much as an entire 12-oz soda).



After a total of 10 hours, there will still be 23.75 mg of caffeine left in your body.



Knowing this, it may be a good idea to make that late evening cup of coffee a decaf!

Deep Parikh

*The views and opinions expressed herein are those of the author and do not necessarily reflect the views of, its affiliates, or its employees.