WASHINGTON: United States researchers have revealed that coffee at night disrupt humans body’s sleep and wakeup cycle.
Coffee before bedtime disrupts the body’s internal clock, making it harder to get to sleep on time and more challenging to wake up in the morning.
The study involved five volunteers who were randomly assigned to consume as much caffeine as contained in a double espresso three hours before bed, or who were exposed to bright lights, or were given a placebo.
Over the course of 49 days, the volunteers were studied under various conditions, and their saliva was regularly tested for levels of the hormone melatonin, which naturally regulates sleep and waking cycles.
They found that those who took caffeine in low-light conditions experienced about a “40-minute phase delay of the circadian melatonin rhythm,” said the study.
Those who were exposed to bright overhead lights three hours before bed saw their circadian clocks bumped back by 85 minutes. Those who took both the caffeine and sat under bright lights were disrupted by 105 minutes.
“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 professor Kenneth Wright of the University of Colorado, Boulder.
