According to a small study, caffeine cannot replace the lost sleep. Researchers found that coffee was ineffective in granting a mental boost to participants who were sleep deprived.
The research involved 48 participants who got only 5 hours of nighttime rest over the last five days. Volunteers were given either a placebo or the equivalent of caffeine from a large cup of coffee.
Neither the study investigators nor the volunteers knew who got the placebo and who got the coffee equivalent. Following three nights of sleep deprivation both groups showed signs of fatigue as their scores on brain tests fell even if they had been given caffeine.
Tracy Jill Doty, senior researcher involved in the study and behavioral biology expert at Walter Reed Army Institute of Research, explained that the findings are important to debunk a myth that coffee could offset performance decline linked to chronic sleep deprivation.
Doty added that the recent research is unique as few studies have tried to assess the impact of caffeine on chronically sleep deprived people. She also said that the findings may help the military in war zones, as soldiers often get sleep restricted and try to compensate with caffeine for the lost sleep.
During the trial, volunteers agreed to sleep at a laboratory for one week and get either caffeine supplements or a placebo twice a day: at 8 a.m. and 12 p.m. They also agreed to be tested for mood swings, reaction time, and mental sharpness. Additionally, they took brain tests every hour for five days in a row.
The only difference between the two groups was that participants on caffeine had better reaction times during the first couple of days of the experiment. Over the last three days, their performance dropped just like in the non-caffeinated group.
Additionally, participants on caffeine reported that their mood was lifted on the first two days, while the placebo group saw no improvement in their mood. Surprisingly, participants who were given caffeine supplements said that they felt more irritated towards the end of the experiment than participants in the control group.
Study authors, however, acknowledged that their small trial had some limitations. For example, it didn’t explore the possibility of raising the amount of caffeine over time as many sleep restricted individuals tend to do.
The study results were revealed June 14 at the Associated Professional Sleep Societies annual gathering in Denver.
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