Thanks to a new study that was recently presented at SLEEP 2016 , caffeine is a good ally to stay more awake, alert and mentally agile if you have slept only a few hours. However, this effect seems to disappear after two continuous days under this sleep deficit .
To demonstrate this, the researchers recruited 48 volunteers to participate in a rather cumbersome experiment, during which they were only allowed to stay in bed for five hours a night, for five nights.
Each day, the participants were given 200 milligram doses of caffeine, to one group, and a placebo, to the other group. The caffeine doses were given at 8 in the morning and another at noon, while they were subjected to a series of cognitive tasks throughout the day . The researchers also measured each participant’s "sleep" using the Stanford Sleepiness Scale and the Maintenance of Wakefulness Test .
Compared to the placebo group, those who received the caffeine were more awake and alert during the first two days of the experiment. However, by the third day, the benefits of the caffeine had completely worn off, and continuing to take it did not produce any improvement in performance .
The data from this study thus suggest that the same daily dose of caffeine is not enough to prevent performance decline through multiple days of restricted sleep. In addition to its impact on cognitive performance, caffeine also raised users’ mood and happiness levels after the first two nights of sleep deprivation.
However, once again this effect disappeared after a third night of insufficient sleep, and in fact left those in the caffeine group more agitated and annoying than those in the placebo group after the third day .
Via | IFLScience
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