Beware of Coffee After Dark

25th September 2015

Read time is about 2 mins

Beware of Coffee After Dark

It’s common knowledge (and common sense) that guzzling a red-eye before bed is a boneheaded move if you have any interest in sleeping. Caffeine, the world’s favorite legal upper, gets us juiced by blocking the sleep-inducing hormone adenosine, which builds up in our bodies over the course of a day. We’ve understood this stimulating process for a long time. But, researchers from Univeristy of Colorado Boulder have unearthed another reason to eschew an evening espresso: Nighttime caffeine delays the circadian clock.

Study author Kenneth Wright runs Boulder’s Sleep and Chronobiology Lab, where he researches everything to do with our sleep-and-wake cycles, including the biological mechanisms underlying our roughly 24-hour biological clocks, disorders marked by broken clocks and the various lifestyle factors that can throw those clocks off schedule. In 2013, Wright, his team and some outdoorsy study volunteers trekked to the Rocky Mountains and ditched all artificial light, even flashlights. After a week, the eight study participants’ circadian clocks had completely synched up with the timing of sunrise and sunset.

More recently, Wright’s traded in pitch-dark wildnerness for dark-roasted beans (experimentally speaking), to investigate the little-understood caffeine-circadian clock connection. He and his team administered caffeine pills (and placebo pills) to study volunteers in different types of lighting (dim or bright) and found that taking a double-espresso-sized dose of caffeine three hours before hitting the sack delays biological clocks by 40 minutes.

Listen to Wright discuss his new study in the Soundcloud clip below:

This article originally published by Van Winkle’s,, the editorial division of Casper Sleep; Copyright 2015. Follow Van Winkle’s on Twitter.


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