Task Progress:
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Data obtained from the RST project included: Time in Bed, Total Sleep Time, Poor Sleep Quality, Sleepiness, Tiredness, Fatigue, Physical Exhaustion, Stress, Workload, Caffeine Consumption, PVT Response Speed, PVT Lapses, PVT Premature Responses, and PVT Performance Score. No medications were reported by either astronaut. Linear mixed effect models with random subject effect were created using SAS version 9.3 and adjusted only for administration time (morning/evening). The five groups that were compared were: N=21 astronauts with valid data from the PVT on ISS 6-month mission, first 6 months of data from astronaut Y, second 6 months of data from astronaut Y, first 6 months of data from astronaut Z, and second 6 months of data from astronaut Z. Paired t-tests were used to compare the first and second 6-month periods for astronaut Y and to compare the first and second 6-month periods for astronaut Z. Independent t-tests were used to compare data from N=21 astronauts on the 6-month mission with the first and second 6-month periods for astronaut Y, and to compare data from N=21 astronauts from the 6-month mission with the first and second 6-month periods for astronaut Z.
Astronaut Y had no significant changes from the first 6 months to the second 6 months in the following in-flight VAS scales: Time in Bed (TIB), Total Sleep Time (TST), Poor Sleep Quality, Sleepiness, Tiredness, Fatigue, Physical Exhaustion, and Workload. Astronaut Y did, however, have a significant increase in subjective Stress ratings from the first 6 months to the second 6 months in-flight.
Relative to PVT-B performance, Astronaut Y had no significant changes from the first to the second 6 months of the 1-year mission in PVT Response Speed or PVT Premature Responses. However, Astronaut Y did have significantly more PVT Lapses in the second 6 months of the mission. Moreover, Astronaut Y had significantly more PVT Lapses in both six month periods of the 1-year mission relative to the N=21 astronauts who undertook 6-month ISS missions. Therefore, Astronaut Y had a lower overall PVT-B Performance Score than the N=21 astronauts from the 6-month mission.
Astronaut Z had no significant changes from the first 6 months to the second 6 months in the following in-flight VAS scales: TST, Poor Sleep Quality, Tiredness, and Fatigue. Astronaut Z did, however, have a significant decrease in TIB, increase in Sleepiness, increase in Physical Exhaustion, decrease in Stress, increase in Workload, and decrease in Caffeine Consumption in the second 6 months relative to the first 6 months.
Relative to PVT-B Performance, Astronaut Z had no significant changes from the first 6 months to the second 6 months of the 1-year mission in PVT Response Speed or PVT Premature Responses. However, Astronaut Z did have significantly less PVT Premature Responses in the second 6 months of the mission. Therefore, Astronaut Z had a significant increase in PVT Performance Score in the second 6 months relative to the first 6 months of the mission. The PVT-B Performance Score of Astronaut Y was more adversely affected by Slam shifts during the first 6 months of the mission than was PVT-B Performance of Astronaut Z.
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