Having one double espresso as much as three hours before sleep induces 40 minutes delay in our circadian clock. This means bedtime is pushed back and mornings are a tough reality to deal with when the alarm rings.
The study was conducted by a joint research team from the University of Colorado Boulder and the Laboratory of Molecular Biology Medical Research Council in Cambridge. In the first study of its kind, researchers found that caffeine intake in the evening induces a delay in our circadian clock that regulates the times of sleep and waking.
The circadian clock works beyond announcing us when it’s bedtime and when it’s time to wake up, regulating cellular activity accordingly as well. According to Professor Kenneth Wright of the University of Colorado Boulder:
“This is the first study to show that caffeine, the mostly widely used psychoactive drug in the world, has an influence on the human circadian clock and cellular timekeeping”.
The study was conducted with the help of five volunteers, counting three women and two men. All five participants participated in the 49 days study that included testing under four different circumstances.
Firstly, they were tested under the effects of a placebo pill and low light. Secondly, they were tested under low-light and a pill containing 200mg of caffeine. Thirdly, the conditions were set for bright light and a placebo pill and lastly they were tested for the effects that a caffeine pill and bright light would have on their circadian clocks and cellular timing.
During the 49 days, saliva samples of all participants were tested for melatonin. Melatonin is a hormone that the pineal gland produces naturally when informed so by the circadian clock. Exposure to light, particularly bright light disrupts the clock and resets it. Caffeine has the same effect. As the circadian clock is reset, melatonin levels, normally at high peak during biological nighttime as signaled by the circadian clock, reset as well. Cellular activity follows.
The results of the study showed that when the participants took the caffeine pill, roughly the equivalent of a double espresso and were exposed to low light, their circadian rhythm was delayed by 40 minutes.
Exposure to bright light delayed the participants’ clocks by 85 minutes, while when combined with the caffeine pill, it resulted in 105 minute delay. For night owls, this is devastating if a strict daily routine has to be followed.
Not only for them, but for everyone, the an advice still stands: do not indulge in the lifestyle that force a chronic lack of sleep and often resetting of the circadian clock. Cells are confused, obesity, liver and heart disease risks are on the rise, your body is tired and often, depression and anxiety are looming around the corner.
The study findings are published in the journal Science Translational Medicine.
Photo Credits: Pexels