Researchers at Stanford University surveyed 50 college students about caffeine intake and found a link between caffeine intake and "time of day"(the time of day when people are most alert or active). Caffeine affects sleep only for larks who are used to going to bed early and getting up early, and does not interfere with sleep for night owls who love to stay up late. For larks, the more caffeine they consumed, the longer they spent awake during sleep, which was not the case for night owls.
The researchers caution that everyone metabolizes caffeine differently, with some people metabolizing it in a matter of hours, while others drink coffee at noon and still have caffeine in their bodies at night. If you're a lark, it's best not to drink too much caffeinated drinks like coffee or tea after noon. (Source: Jinyang.com)
