Caffeine has been associated with increasing stress levels. So, especially during the holiday season, keep caffeine intake to a minimum. Also, remember that if consumed late in the day caffeine can interfere with sleep patterns. Fact: Caffeine has a half-life of an average of four hours, meaning it will take your body four hours to rid itself of half the amount of caffeine that you have consumed. After eight hours, your body will contain one-quarter of the original amount and, after 12 hours, your body will still contain one-eighth of what you first drank.