Caffeine Takes Toll on Morning People's Sleep

Morning person? You might want to go easy on the coffee. A new study suggests that caffeine intake during the day is more likely to disrupt a morning person's sleep than a night owl's. Researchers had 50 college students track their caffeine intake and sleep patterns for a week; the students were equipped with wrist sensors that revealed whether they'd woken up during the night, Scientific American reports.

Since they were typical sleep-deprived college kids, they tended to sleep well regardless of how much caffeine they consumed, says a researcher at Stanford. Still, the more caffeine present in the early birds' systems, the longer they spent awake after first dozing off. That wasn't the case for the night owls, however. More research is needed following the study, which researchers say was the first to compare caffeine intake with "chronotype"—a person's wakefulness habits. (More coffee stories.)