When we don't get enough sleep, we try to compensate by drinking too much coffee. But a new study shows that caffeine can help with certain simple tasks, but not with complex mental tasks that are affected by lack of sleep. The study results were published inJournal of Experimental Psychology: Learning, Memory, and Cognitionpublished.
Lack of sleepis linked to virtually every poor health condition imaginable, including a far higher risk of heart disease and stroke. There is also evidence that inadequate sleep can lead to poorer blood sugar control in people with diabetes and that diabetes-related symptoms can make it difficult to fall or stay asleep. But as the latest study shows, caffeine consumption can only partially compensate for the mental impairment caused by lack of sleep.
The study participants were 276 adults who were asked to complete a sequence of two different tasks on two different occasions. The first occasion was in the evening, and the two tasks involved either vigilant attention—basically reaction time—or placekeeping, tracking a sequence of objects or events. After completing both tasks, participants were randomly assigned to either go home and sleep as usual or stay up all night in the laboratory where the study took place. In the morning, the participants who were sleeping at home returned, and all participants took either a capsule containing 200 milligrams of caffeine or a placebo. After enough time had passed for the caffeine to be activated in the body, the participants completed the two tasks again.
Not surprisingly, participants who had not slept performed worse on measures of vigilant attention and location fixation. However, caffeine consumption did not help with either task - while it offset some of the loss of alert attention caused by sleep deprivation, it did not significantly improve location determination compared to sleep-deprived participants who did not consume caffeine. Tracking the order of objects or events is considered to be cognitively more complex than simply paying attention to a signal and responding to it - so these results show that caffeine may help with simple mental tasks related to sleep deprivation, but not necessarily tasks , which require greater brain power.
This finding, the researchers wrote, "suggests that caffeine has limited potential to reduce sleep-deprived-induced error rates on job tasks." In other words, don't expect to be able to perform work-related tasks well if you haven't gotten enough sleep, even if you drink a lot of coffee. Paired with the big long termHealth risks associated with lack of sleepThese results give us many reasons to prioritize sleep as much as possible.
Stepan, M. E., Altmann, E. M., & Fenn, K. M. (2021). Caffeine selectively mitigates cognitive deficits caused by sleep deprivation.Journal of Experimental Psychology: Learning, Memory, and Cognition
