University students often rely on caffeine to stay alert and focused, but the extent to which it actually supports cognitive performance is still uncertain, therefor this study explored how natural variation in caffeine use relates to working memory, measured through an N-back task. 52 students from different universities in Stockholm participated by completing both the memory test and a questionnaire about their recent caffeine intake, sleep habits, and potential distractions during testing. While no significant links were found between how much caffeine students usually consume, either daily or weekly, and their test scores, the timing of consumption turned out to matter. Students who had consumed caffeine closer to the test session tended to perform better, suggesting a time sensitive effect. On the other hand, sleep quality, hours of sleep, and environmental noise did not show any clear relationship to performance. These findings suggest that it’s not necessarily the amount of caffeine that makes a difference, but when it is consumed. The results may offer helpful insights for students seeking to improve their cognitive focus before mentally demanding tasks, but further studies with experimental designs are needed to draw firmer conclusions.