Buzz
For coffee lovers, here’s some disheartening news. Although many of us are aware that consuming coffee late in the day can hinder sleep, the underlying reasons remain unclear. While it might appear straightforward—coffee boosts energy, and excess energy disrupts sleep—research reveals that caffeine’s impact on our bodies is far more intricate.
Scientists from the MRC Laboratory of Molecular Biology and the University of Colorado discovered that caffeine influences our internal clock. As reported in Science Translational Medicine, “caffeine—a widely accessible, legal, and psychoactive substance—introduces a delay into the roughly 24-hour metabolic cycle that synchronizes your body with the external world.” They observed that evening caffeine consumption postpones the brain’s secretion of melatonin, the hormone responsible for inducing sleep.
Given the numerous factors—such as lighting and electronic device usage—that can disrupt sleep, the researchers conducted a tightly controlled experiment. Over 49 days, they observed five individuals in a regulated environment. Each night before sleep, participants were administered either caffeine tablets or a placebo, alongside varying levels of light exposure.
While the researchers noted that bright light had the most substantial effect on the circadian rhythm, caffeine also played a notable role, pushing back participants' internal clocks by up to 40 minutes. Although this study probably won’t curb our caffeine intake entirely, it’s certainly worth considering the next time we’re tempted by that final cup of coffee at night.
