A new study exploring the impact of repeated sleep loss during a simulated working week has found that consuming caffeinated coffee during the day helps to minimize reductions in attention and cognitive function, compared to decaffeinated coffee.

While this effect occurred in the first 3 to 4 days of restricted sleep, by the fifth day (the final day in the study), no difference was seen between regular and decaf coffee drinkers. This suggests that the beneficial effects of coffee for people with restricted sleep are temporary, the authors say.

“Previous research suggests that acute consumption of caffeinated coffee can reduce the impact of sleep deprivation on deficits of attention and cognitive function in a short-term setting,” says Denise Lange, study co-author, in a release. “This study is among the first to examine whether this effect can be translated into a real-world situation, where caffeinated drinks are commonly consumed every day by people who experience chronic sleep restriction. Our study indicates that moderate coffee intake can mitigate some repercussions of reduced sleep over a few days; however, this is not a substitute for a good night’s sleep in the long term.”

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The study was conducted at the Institute of Aerospace Medicine, in Cologne Germany. Twenty-six participants carrying a distinct genotype of the gene encoding the adenosine A2A receptor were randomly assigned to groups either drinking caffeinated coffee (containing 300 mg caffeine) or decaffeinated coffee under double-blind conditions. During five days, the sleep of all participants was restricted to five hours per night and each day they rated their subjective sleepiness and were tested on levels of vigilance, alertness, reaction-time, accuracy, and memory.

The study is published in Progress in Neuro-Psychopharmacology & Biological Psychiatry.

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