Researchers studying the outcome of caffeine on our circadian clock have made a startling , yet unsurprising uncovering : Coffee before bed delays our internal timekeeping system . The findings were write inScience Translational Medicinethis week .
We live on a roughly 24 - time of day rhythm . The master clock in our brain that coordinates cellular timekeeping throughout our entire dead body is reset by exposure to light . Researchers from the University of Colorado Boulder and MRC Laboratory of Molecular Biology recruited five healthy someone for a 49 - day subject field . On some days , the participants took a placebo , but on others , they were given a caffeine pill – equivalent to two shots of espresso – three hour before going to seam .
Caffeine , the squad ascertain , lengthened the participants ’ circadian flow strongly . One post - dinner dose delay their interior clocks by about 40 minutes on middling . " This is the first study to show that caffeine , the mostly widely used psychotropic drug in the existence , has an influence on the human circadian clock,“CU - Boulder ’s Kenneth Wrightsaid in astatement .
The team also desire to see how nighttime caffeine compared with nighttime exposure to bright light – an environmental cue known to lengthen the circadian phase and disrupt sleep . So , subject taking either a caffeine or placebo birth control pill were also were unwrap to either dim or bright overhead lighting for three hours beginning at each someone ’s normal bedtime . Turns out , the shift due to consuming bedtime caffeine is about one-half as long as that stimulate by evening photograph to bright light . But while lustrous light induced a delay of about 85 arcminute , volunteer combining the caffeine pill with bright light go through a 105 - min postponement in their circadian phase .
When the investigator expose cultivated human cell to chronic levels of caffeine , they chance that the pith prevents adenosine , a sleep - promoting neurotransmitter , from constipate to its sensory receptor . And this influences cyclic AMP signaling , which act a key role in the control of the circadian clock .
The finding suggest that tardy - night coffee drinking may contribute to the rise in eternal rest problems , but properly timed caffein consumption may help readjust the circadian clock for people suffering from jetlag after flying westward .
