No substitute: When you’re sleep deprived, caffeine cannot fully replace rest

EAST LANSING, Mich. — Caffeine is a great tool to add some pep to your step, but researchers from Michigan State University warn not to lean on coffee, energy drinks, and the like too much. Their study finds caffeine is no substitute for actual sleep.

Study authors investigated just how effective caffeine can be when it comes to combating and overriding the cognitive toll of a sleepless night. After staying up all night, researchers asked a group of 275 participants to complete both a simple attention task and a more challenging “placekeeping” task. The more complex assignment involved the completion of various tasks in a specific order, all without skipping or repeating any of the prior steps.

Regarding placekeeping specifically, the team says this is the first study ever to analyze the effect of caffeine while sleep deprived.

“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 placekeeping task for most participants,” psychology associate professor Kimberly Fenn says in a university release.

“Caffeine may improve the ability to stay awake and attend to a task, but it doesn’t do much to prevent the sort of procedural errors that can cause things like medical mistakes and car accidents,” she adds.

Lack of sleep can lead to dangerous mistakes

Insomnia and sleep issues are an all too common problem in the United States, and the pandemic has only made the issue worse and more widespread. Pandemics aren’t exactly conducive to relaxation. Sleeping poorly for too long will typically lead to poorer cognition, mood, and even immune health.

“Caffeine increases energy, reduces sleepiness and can even improve mood, but it absolutely does not replace a full night of sleep,” Fenn notes. “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.”

“If we had found that caffeine significantly reduced procedural errors under conditions of sleep deprivation, this would have broad implications for individuals who must perform high stakes procedures with insufficient sleep, like surgeons, pilots and police officers,” she concludes. “Instead, our findings underscore the importance of prioritizing sleep.”

The study appears in the Journal of Experimental Psychology: Learning, Memory, and Cognition.