Once you consume an energy drink it takes five to six hours for your body to reduce the content of caffeine in your bloodstream by 50%. Women on birth control tablets require double the length for their body to reduce it. For most people it takes 12 hours to fully remove caffeine from their bloodstream. The speed at which this happens does depend on many factors from age to activity. As caffeine is a drug those who regularly drink items with it can feel withdrawal symptoms 12-24 hours after the last dose. These often include headaches, irritability, and constipation. https://www.walesonline.co.uk/news/health/what-happens-your-body-hours-12225076
According to Medical News Today https://www.medicalnewstoday.com/articles/298202#Sugar-crashes,-energy-slumps-and-caffeine-withdrawal, it takes an average of 12 hours for the body to completely remove the caffeine from the bloodstream, though this does depend on individual factors. Studies have also shown that your body only needs 7-12 days to become tolerant to your regular caffeine dosage. This means that you won’t feel the energy drink effect as much as earlier.