Researchers at Michigan State University's Sleep and Learning Lab assessed how effective caffeine was in counteracting the negative effects of sleep deprivation on cognition. The study was led by psychology associate professor Kimberly Fenn and published in the Journal of Experimental Psychology: Learning, Memory, & Cognition.
More than 275 study participants completed an attention task and a "place-keeping" task in the evening, then were then randomly assigned to either stay awake overnight in the lab or sleep at home. In the morning, participants who slept returned to the lab, and all participants consumed a capsule that contained either 200 mg of caffeine or placebo, before completing the tasks again.
Results led the researchers to conclude that consistently being deprived of a good night's sleep not only affects cognition and alters mood, but can eventually take a toll on immunity.
"We found that sleep deprivation impaired performance on both types of tasks and that having caffeine helped people successfully achieve the easier task. However, it had little effect on performance on the place-keeping task for most participants," explained Fenn.
"Caffeine increases energy, reduces sleepiness and can even improve mood, but it absolutely does not replace a full night of sleep," she continued. "Although people may feel as if they can combat sleep deprivation with caffeine, their performance on higher-level tasks will likely still be impaired. This is one of the reasons why sleep deprivation can be so dangerous."