Audio Script
CU study: Caffeine before bedtime disruptive to biological sleep clock Sept. 16, 2015 Kenneth Wright It’s no secret that slugging down coffee and other caffeinated drinks at night can disrupt sleep. But a new CU-Boulder study shows for the first time that evening caffeine delays our internal clock that tells us when to get ready for sleep and when to awaken, says Professor Ken Wright, who co-led the study. CUT 1 “Caffeine is the most popular drug in the world. And we’ve known for a long time that if you drink caffeine it could wake you up and also disturb your sleep. What was unknown is whether or not caffeine could affect the time of the internal circadian clock in humans. (:14) We found that if we give someone the equivalent of a double espresso three hours before they would normally go to sleep, that we’re able to delay the timing of their internal circadian clock.” (:25) How long is that delay in the roughly 24-hour circadian, or biological, clock? About 40 minutes, says Wright. And additional findings from the study show that it’s not only sleep that is impacted by caffeine, says Wright, but other aspects of the human body as well. CUT 2 “We’re also able to determine by looking at human cells how caffeine affected the timing of cellular clocks. And we’re able to show that caffeine causes changes in chemicals within the cell that alter the timing of that cell. (:14) By pushing our clocks later, this says that everything that is timed by this circadian clock, such as sleep timing, the release of hormones, when we’re performing at our best, and when we’re most sleepy, are also changing.” (:28) Wright says he anticipates this discovery will open up new avenues of research concerning how caffeine affects the human body. CUT 3 “I think one of the takeaways from our study is that now we understand that caffeine affects another fundamental component of our biology, this circadian timing. And this is very different than sleep and wakefulness only because we know we have clocks throughout the rest of our body besides our brain. (:17) And so if caffeine is affecting the clocks in our liver and in our muscles, it may be affecting how well those particular organs or tissues are functioning. And so I think that there’s going to be a lot of other research to try and understand how caffeine affects us.” (:30) The new results also could benefit travelers, says Wright. He says properly timed caffeine use could help shift the circadian clocks of those flying west over multiple time zones. John O’Neill with the Medical Research Council’s Laboratory of Molecular Biology in Cambridge, England is co-led on the study. -CU-
