WIKIMEDIA, JULIUS SCHORZMANCoffee, tea, and other caffeinated drinks can make a person feel more awake and alert, but new research suggests that, when consumed in the evening, caffeine might also delay the body’s internal clock. A paper published in Science Translational Medicine today (September 16) shows that people given a dose of caffeine a few hours before their normal bedtimes exhibited a delay in their circadian rhythms of more than half an hour.
“We already knew that caffeine is a stimulant and can keep you awake and make it difficult to fall asleep at night if taken too close to bedtime,” said behavioral neurologist Charmane Eastman of Rush University in Chicago, who was not involved in the work. “This study shows that caffeine can also make your internal circadian body clock later, which could make it difficult to fall asleep the next night even if you don’t take caffeine again.”
A person’s circadian rhythms are established by a variety of temporal cues such as sunrise and sunset, feeding times, body temperature fluctuations, and levels of certain hormones. And resisting these cues is hard. Many people’s sleep and daily routines are disturbed by the one-hour shift to daylight saving, ...
