A new study has shown that caffeine at night delays human circadian clock by 40 minutes.
The study led by the University of Colorado Boulder and the Medical Research Council’s Laboratory of Molecular Biology in Cambridge, England shows for the first time that evening caffeine delays the internal circadian clock that tells us when to get ready for sleep and when to prepare to wake up.
The research team showed the amount of caffeine in a double espresso or its equivalent three hours before bedtime induced a 40-minute phase delay in the roughly 24-hour human biological clock.
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, said researcher Kenneth Wright, adding that it also provides new and exciting insights into the effects of caffeine on human physiology.
The new results could benefit travelers. Properly timed caffeine use could help shift the circadian clocks of those flying west over multiple time zones, said Wright.
The research is being published online in Science Translational Medicine.