You've had a week just like Craig David. Met a girl at the pub on Monday, took her for a drink on Tuesday, and were up all night making love by Wednesday. Now it's Thursday and you may be relying on the work coffee machine to carry you through to that chilled Friday, but new research suggests that after three nights of poor sleep, caffeine ain't gonna help your tired ass.
Presented on Monday at the SLEEP conference in Denver, Colorado—an annual meeting of the Sleep Research Society and the American Academy of Sleep Medicine—the study claims that "after restricting sleep to five hours per night, caffeine use no longer improved alertness or performance after three nights."
That's right, not even the triple-shot espresso can help you now.
Tracy Jill Doty, lead author of the study and cognitive neuroscientist for the Walter Reed Army Institute of Research, said in a press release that the research had important implications for the widely accepted view that coffee keeps you buzzing.
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She explained: "These results are important, because caffeine is a stimulant widely used to counteract performance decline following periods of restricted sleep. The data from this study suggests that the same effective daily dose of caffeine is not sufficient to prevent performance decline over multiple days of restricted sleep."
Following a five-day period of ten hours sleep a night, the 48 individuals involved in the study had their sleep limited to five hours a night. During this period, researchers gave half of the group 200 milligrams of caffeine (around the amount found in a regular cup of strong coffee) twice daily, while the other half received a placebo. Cognitive tasks and mood tests were then carried out during their waking hours.
The researchers found that "relative to placebo, caffeine significantly improved" task performance during the first two days and "effectively increased sleep latencies and improved ratings of happiness." But the wild coffee crash came over the final days of sleep restriction, as those in the caffeine group "rated themselves more annoyed than those in the placebo group."
READ MORE: A Single Coffee Drink a Day Could Ruin Your Entire Diet
While previous studies have found that caffeine consumption is linked with protecting the development of depression and associations with improved cognitive performance, Doty and her team's findings are unusual. She expressed surprise at the fact "that the performance advantage conferred by two daily 200 milligram doses of caffeine was lost after three nights of sleep restriction."
Maybe the solution is to get some of that old fashioned beauty sleep. Or, at the very least, a quick nap in the disabled loos at work.