Caffeine Affects Early Birds More

A cappuccino at 9 p.m. is never a good idea, even if you order decaf, because sometimes baristas lie (you know who you are). But even caffeine during the day can affect "morning people" while they're sleeping, a new study shows.

Stanford researchers studied 50 college kids, monitoring their caffeine intake, sleeping and waking times, and movement during sleep.

The results, published in the journal Sleep Medicine, found that early risers tend to wake up more during the night if they had more caffeine during the day. Students who ususally sleep in, however, slept the same regardless of the amount of caffeine they had.

The act of falling asleep wasn't affected by coffee intake, either. Researchers noted that all subjects fell asleep easily when they got into bed, since they're all sleep-deprived from studying so hard, of course.