| Abstrakt: |
INTRODUCTION: Astronaut crews have historically averaged six hours of sleep per night. In recent years, ISS crew have had more stable schedules, with consistent bed and wake times. Despite these improvements, there remain uncontrollable operational events that require crewmembers to shift their sleep. It is unclear what impact these acute schedule changes have on sleep and performance outcomes. The aims of this analysis are to characterize approaches to sleep shifting, including shifting sleep earlier or later and splitting sleep, and to determine the impact on sleep outcomes and crew alertness and performance. METHODS: Crewmembers (n = 19) on the ISS were provided with actiwatches that they wore for two bouts of data collection before flight, inflight, and immediately upon return to Earth. We first characterized the impact of "split sleep," whereby a person attempts sleep on two separate occasions in a 24-hour period that are similar in length, and its impact on sleep outcomes. RESULTS: Nine crewmembers engaged in 14 episodes of split sleep while inflight. These periods surrounded six separate visiting vehicle events that interfered with their nominal sleep window (2130 to 0600). The first sleep opportunity typically took place during the afternoon before the disrupting event, while the second episode took place the following morning. On average, the first sleep opportunity was shorter than the second (M1=2.79±0.74 vs. M2=4.28±1.56), as were sleep duration (M1=2.65±0.81 vs. M2=4.11±1.57) and efficiency (M1=76.06±13.43 vs. M2=83.49±8.46). On inflight nights with no split sleep, these crewmembers averaged 6.71±0.52 hours of sleep per night with a sleep efficiency of 83.51±2.61. DISCUSSION: Next, we will compare the crewmembers' split sleep outcomes to those from other strategies to determine which yield the best sleep outcomes. We will use biomathematical modeling to analyze the predicted alertness on these schedules. Understanding these impacts will aid in decision making for future spaceflight operations and will inform on the impacts of various strategies to adjust sleep and help guide scheduling in future missions where consistent schedules may not be possible. Learning Objectives 1. Participants will learn how sleep shifts impact crewmember sleep outcomes. 2. Participants will learn how sleep shifts impact predicted crew alertness. [ABSTRACT FROM AUTHOR] |
