0330 Caffeine Consumption Aboard the International Space Station

Abstract Introduction Caffeine is the most widely used performance-enhancing drug on Earth and astronaut crews have access to liquid coffee. While caffeine is a potent countermeasure to improve alertness and performance, it can also interfere with sleep. This can lead to performance deficits on the following day, driving a cycle of caffeine use to counter the effects of caffeine-induced sleep disruption. Caffeine availability may be limited during future Artemis and/or Mars missions. Therefore, we aimed to characterize how caffeine is used aboard the International Space Station (ISS) to better inform future spaceflight operations. Methods Daily caffeine consumption was determined from food and beverage intake tracking for 25 astronauts (11F) on 6-month International Space Station (ISS) missions. Data were recorded using the ISS Food Intake Tracker iPad App or other detailed recording technique. On average, crew recorded dietary intake on 179.7±68.6 (mean±SD) days inflight. Results Astronauts consumed 97±92 mg caffeine per day. All astronauts (25/25) in this study consumed caffeine at some point during flight, though the frequency, amounts, and regularity differed across crewmembers. Approximately a quarter of crewmembers were regular caffeine consumers (6/25), i.e., they ingested at least 90 mg caffeine (equivalent to one cup of coffee) on 90% of inflight days. Conclusion Our findings demonstrate that caffeine is regularly consumed by astronauts, though consumption patterns vary across individuals. Future analyses will involve evaluating these data in light of sleep and performance outcomes. This information will provide us with an understanding of how caffeine is being used inflight to help guide future countermeasure development. Support (if any)