Coffee 101: Morning Joe Keeps You Awake By Tweaking Your Biological Clock

By Peter R - 18 Sep '15 15:39PM

Late nights are nearly impossible without coffee but did you know caffeine also disrupts your biological clock?

A new study claims that coffee can delay release of the hormone Melatonin by about 40 minutes. The hormone is the hands of the circadian biological clock. During night hours, the hormone is released in relatively large quantities in the brain to make the body fall asleep, according to Live Science.

For the study, researchers recruited three female and two male participants. Each of the subjects was tested under four conditions. They were put in low light conditions and given a placebo pill, low light and a 200 mg caffeine pill, bright light and placebo, and bright light and the caffeine pill. Caffeine pill contains the same amount of caffeine that two shots of espresso contain. Melatonin testing was done through saliva samples.

Researchers found that caffeine pill delayed release of melatonin by about 40 minutes when participants took caffeine pill under low light conditions. When caffeine pill was taken under bright light conditions, it delayed the clock by 105 minutes.

The study also showed that bright light alone can delay the clock by 85 minutes.

"This is the first study to show that caffeine, mostly widely used psychoactive drug in the world, has an influence on the human circadian clock. It also provides new and exciting insights into the effects of caffeine on human physiology," said Kenneth Wright, a professor in CU-Boulder's Department of Integrative Physiology.

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