When we’ve had a bad night of sleep, many of us reach for a big cup of coffee to help get through the day reasonably alert. However, a new study found that caffeine use no longer improved alertness or performance after three nights of poor sleep.
Results show that compared to a placebo, caffeine significantly improved performance during the first 2 days, but not the last 3 days of sleep restriction.
“We were particularly surprised that the performance advantage conferred by two daily 200 mg doses of caffeine was lost after three nights of sleep restriction,” said lead author Tracy Jill Doty, PhD, research scientist at Walter Reed Army Institute of Research. “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.”
The research abstract was published recently in an online supplement of the journal Sleep.
The study group consisted of 48 healthy individuals who participated in a double blind, placebo-controlled study. Sleep was restricted to five hours of time in bed for a total of five days. Participants were administered either 200 mg of caffeine or a placebo twice daily. A cognitive task battery was administered hourly during the wake periods.
If you find that you’re sleeping poorly night after night, consult your doctor. If physical reasons have been ruled out, it may be time to take a good look at your sleep environment, including your bedding.
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