Caffeine can help with the performance of certain simple tasks, but fails to help with mentally complex tasks that are impaired by sleep deprivation, according to a new study published in the Journal of Experimental Psychology: Learning, Memory, and Cognition.
Lack of sleep is linked to practically every bad health outcome imaginable, including a far higher risk for poor outcomes related to heart disease and stroke — outcomes that should be particularly concerning to people with diabetes, since heart disease is the leading cause of death in people with diabetes. There’s also evidence that not getting enough sleep could lead to worse blood glucose control in people with diabetes, and that symptoms related to diabetes can make it harder to fall or stay asleep — potentially making sleep a particular challenge for many people with diabetes. But as the latest study shows, there’s only so much that consuming caffeine can do to make up for the mental impairment caused by lost sleep.
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The study participants were 276 adults who completed 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 — reaction time, basically — or placekeeping, keeping track of a sequence of objects or events. After they completed both of these tasks, participants were randomly assigned either to go home and sleep as usual, or to stay up all night in the lab where the study took place. In the morning, the participants who slept at home returned, and all participants consumed either a capsule containing 200 milligrams of caffeine or a placebo (inactive pill). After enough time for the caffeine to become active in the body, participants then completed both vigilant attention and placekeeping tasks again.
Caffeine found not to compensate for lack of sleep
Not surprisingly, participants who hadn’t slept performed worse in measures of both vigilant attention and placekeeping. But consuming caffeine didn’t help with both tasks — it made up for some of the loss of vigilant attention caused by sleep deprivation, but didn’t significantly improve placekeeping compared with sleep-deprived participants who didn’t consume caffeine. Keeping track of the order of objects or events is considered more cognitively complex than simply paying attention, and reacting, to a signal — so these results demonstrate that caffeine may help with simple mental tasks in the context of sleep deprivation, but not necessarily tasks that demand higher-level brain performance.
This finding, the researchers wrote, “suggests that caffeine has limited potential to reduce procedural error rates in occupational settings” that is caused by a lack of sleep. In other words, don’t expect to perform work-related tasks well if you haven’t slept enough, even if you drink plenty of coffee. Paired with the major long-term health risks of not sleeping enough, these results give people with diabetes plenty of reasons to prioritize sleep to the greatest degree possible.
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