Abstract
Many college students struggle to perform well on exams in the early morning. Although students drink caffeinated beverages to feel more awake, it is unclear whether these actually improve performance. After consuming coffee (caffeinated or decaffeinated), college-age adults completed implicit and explicit memory tasks in the early morning and late afternoon (Experiment 1). During the morning, participants ingesting caffeine demonstrated a striking improvement in explicit memory, but not implicit memory. Caffeine did not alter memory performance in the afternoon. In Experiment 2, participants engaged in cardiovascular exercise in order to examine whether increases in physiological arousal similarly improved memory. Despite clear increases in physiological arousal, exercise did not improve memory performance compared to a stretching control condition. These results suggest that caffeine has a specific benefit for memory during students’ non-optimal time of day – early morning. These findings have real-world implications for students taking morning exams.
Highlights
As any college student will tell you, the worst time to take a class is first thing in the morning
We considered whether caffeine could overcome the well-documented decrease in memory performance among older adults during the late afternoon, when most older adults experience their circadian low point
Consuming caffeinated coffee results in significantly higher memory performance on an explicit cued–recall task in the early morning, but not in the late afternoon. These results are consistent with the hypothesis that caffeine benefits cognition during suboptimal conditions (Ryan et al, 2002; Nehlig, 2010) − in this case, during the low point in young adults’ circadian rhythm
Summary
As any college student will tell you, the worst time to take a class is first thing in the morning. Many classes and entrance exams are only offered during the time when most students are at their physiological low point of the day, as measured by body temperature, skin conductance, and heart rate (Horne and Ostberg, 1976; Bailey and Heitkemper, 2001). This circadian slump comes with a cognitive cost. Many students rely on coffee – caffeine – to get them through those early morning exams.
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