Coffee, the world's most popular psychostimulant, sparks debate over its health benefits (see Should you drink coffee?) versus potential downsides. One clear effect: it hinders sleep by blocking adenosine receptors, key promoters of drowsiness.
A recent U.S. study demonstrates coffee does more than stimulate—it disrupts our circadian rhythm, typically governed by light exposure. Our internal clock follows a 24-hour cycle, dictating sleep and wake times based on light cues.
Published in Science Translational Medicine, the research found that caffeine consumed in low-light conditions delayed participants' day-night rhythm by 40 minutes compared to a placebo group. This explains why evening coffee leads to later bedtimes and wake-ups.
