Crew Alertness Management on the Flight Deck: Cognitive and Vigilance Performance

This project had three broad goals: (1) to identify environmental and organismic risks to performance of long-haul cockpit crews; (2) to assess how cognitive and psychomotor vigilance performance, and subjective measures of alertness, were affected by work-rest schedules typical of long-haul cockpit crews; and (3) to determine the alertness-promoting effectiveness of behavioral and technological countermeasures to fatigue on the flight deck. During the course of the research, a number of studies were completed in cooperation with the NASA Ames Fatigue Countermeasures Program. The publications emerging from this project are listed in a bibliography in the appendix. Progress toward these goals will be summarized below according to the period in which it was accomplished

PER3 Polymorphism Predicts Cumulative Sleep Homeostatic but Not Neurobehavioral Changes to Chronic Partial Sleep Deprivation

The variable number tandem repeat (VNTR) polymorphism 5-repeat allele of the circadian gene PERIOD3 (PER3(5/5)) has been associated with cognitive decline at a specific circadian phase in response to a night of total sleep deprivation (TSD), relative to the 4-repeat allele (PER3(4/4)). PER3(5/5) has also been related to higher sleep homeostasis, which is thought to underlie this cognitive vulnerability. To date, no study has used a candidate gene approach to investigate the response to chronic partial sleep deprivation (PSD), a condition distinct from TSD and one commonly experienced by millions of people on a daily and persistent basis. We evaluated whether the PER3 VNTR polymorphism contributed to cumulative neurobehavioral deficits and sleep homeostatic responses during PSD.PER3(5/5) (n = 14), PER3(4/5) (n = 63) and PER3(4/4) (n = 52) healthy adults (aged 22-45 y) demonstrated large, but equivalent cumulative decreases in cognitive performance and physiological alertness, and cumulative increases in sleepiness across 5 nights of sleep restricted to 4 h per night. Such effects were accompanied by increasing daily inter-subject variability in all groups. The PER3 genotypes did not differ significantly at baseline in habitual sleep, physiological sleep structure, circadian phase, physiological sleepiness, cognitive performance, or subjective sleepiness, although during PSD, PER3(5/5) subjects had slightly but reliably elevated sleep homeostatic pressure as measured physiologically by EEG slow-wave energy in non-rapid eye movement sleep compared with PER3(4/4) subjects. PER3 genotypic and allelic frequencies did not differ significantly between Caucasians and African Americans.The PER3 VNTR polymorphism was not associated with individual differences in neurobehavioral responses to PSD, although it was related to one marker of sleep homoeostatic response during PSD. The comparability of PER3 genotypes at baseline and their equivalent inter-individual vulnerability to sleep restriction indicate that PER3 does not contribute to the neurobehavioral effects of chronic sleep loss

Principles and Guidelines for Duty and Rest Scheduling in Commercial Aviation

The aviation industry requires 24-hour activities to meet operational demands. Growth in global long-haul, regional, overnight cargo, and short-haul domestic operations will continue to increase these round-the-clock requirements. Flight crews must be available to support 24-hour-a-day operations to meet these industry demands. Both domestic and international aviation can also require crossing multiple time zones. Therefore, shift work, night work, irregular work schedules, unpredictable work schedules, and dm zone changes will continue to be commonplace components of the aviation industry. These factors pose known challenges to human physiology, and because they result in performance-impairing fatigue, they pose a risk to safety. It is critical to acknowledge and, whenever possible, incorporate scientific information on fatigue, human sleep, and circadian physiology into 24-hour aviation operations. Utilization of such scientific information can help promote crew performance and alertness during flight operations and thereby maintain and improve the safety margin

Electrocortical Evidence for Impaired Affective Picture Processing after Long-Term Immobilization

The neurobehavioral risks associated with spaceflight are not well understood. In particular, little attention has been paid on the role of resilience, social processes and emotion regulation during long-duration spaceflight. Bed rest is a well-established spaceflight analogue that combines the adaptations associated with physical inactivity and semi-isolation and confinement. We here investigated the effects of 30 days of 6 degrees head-down tilt bed rest on affective picture processing using event-related potentials (ERP) in healthy men. Compared to a control group, bed rest participants showed significantly decreased P300 and LPP amplitudes to pleasant and unpleasant stimuli, especially in centroparietal regions, after 30 days of bed rest. Source localization revealed a bilateral lower activity in the posterior cingulate gyrus, insula and precuneus in the bed rest group in both ERP time frames for emotional, but not neutral stimuli

Psychomotor Vigilance Self Test on ISS (Reaction Self Test on Expeditions 21 and 22)

The experiment addresses the following high-priority NASA Risk Gaps in the Behavioral Health and Performance (BHP) area: 1) Identify brief, valid objective measures of changes in cognitive functions during spaceflight that astronauts can use with minimal burden. 2) Find a practical objective aid for astronauts to quickly identify and manage the effects of fatigue (from sleep loss, circadian disruptions, workload and other factors) on their performance during space flight

Sleep deprivation impairs object-selective attention: A view from the ventral visual cortex

10.1371/journal.pone.0009087PLoS ONE52

Crew factors in flight operations 9: Effects of planned cockpit rest on crew performance and alertness in long-haul operations

This study examined the effectiveness of a planned cockpit rest period to improve alertness and performance in long-haul flight operations. The Rest Group (12 crew members) was allowed a planned 40 minute rest period during the low workload, cruise portion of the flight, while the No-Rest Group (9 crew members) had a 40 minute planned control period when they maintained usual flight activities. Measures used in the study included continuous ambulatory recordings of brain wave and eye movement activity, a reaction time/vigilance task, a wrist activity monitor, in-flight fatigue and alertness ratings, a daily log for noting sleep periods, meals, exercise, flight and duty periods, and the NASA Background Questionnaire. The Rest Group pilots slept on 93 percent of the opportunities, falling asleep in 5.6 minutes and sleeping for 25.8 minutes. This nap was associated with improved physiological alertness and performance compared to the No-Rest Group. The benefits of the nap were observed through the critical descent and landing phases of flight. The nap did not affect layover sleep or the cumulative sleep debt. The nap procedures were implemented with minimal disruption to usual flight operations and there were no reported or identified concerns regarding safety

Serum Micronutrient Status, Sleep Quality and Neurobehavioral Function Among Early Adolescents

Objective: To examine associations between serum micronutrients and neurobehavioral function and the mediating role of sleep quality in early adolescents. Design: In this cross-sectional study, peripheral blood samples were analyzed for iron and zinc levels. The Pittsburgh Sleep Quality Index and Penn Computerized Neurocognitive Battery were used to assess sleep quality and neurobehavioral function, respectively. The generalized linear regressions (bootstrap) were performed to estimate the associations. Setting: Jintan, China Participants: 226 adolescents (106 females) from the Jintan Child Cohort study. Results: Adolescents with low iron (\u3c 75 ug/dl) (OR=1.29, p=0.04) and low zinc (\u3c 70 ug/dl) (OR=1.58, p0.05). Conclusion: Iron and zinc deficiencies may possibly be associated with poor sleep and neurobehavioral function among early adolescents. Poor sleep may partially mediate the relationship between micronutrients and neurobehavioral function

Flight controller alertness and performance during MOD shiftwork operations

Decreased alertness and performance associated with fatigue, sleep loss, and circadian disruption are issues faced by a diverse range of shiftwork operations. During STS operations, MOD personnel provide 24 hr. coverage of critical tasks. A joint JSC and ARC project was undertaken to examine these issues in flight controllers during MOD shiftwork operations. An initial operational test of procedures and measures was conducted during STS-53 in Dec. 1992. The study measures included a background questionnaire, a subjective daily logbook completed on a 24 hr. basis (to report sleep patterns, work periods, etc.), and an 8 minute performance and mood test battery administered at the beginning, middle, and end of each shift period. Seventeen Flight controllers representing the 3 Orbit shifts participated. The initial results clearly support further data collection during other STS missions to document baseline levels of alertness and performance during MOD shiftwork operations. These issues are especially pertinent for the night shift operations and the acute phase advance required for the transition of day shift personnel into the night for shuttle launch. Implementation and evaluation of the countermeasure strategies to maximize alertness and performance is planned. As STS missions extend to further extended duration orbiters, timelines and planning for 24 circadian disruption will remain highly relevant in the MOD environment

Two nights of recovery sleep restores hippocampal connectivity but not episodic memory after total sleep deprivation

Sleep deprivation significantly impairs a range of cognitive and brain function, particularly episodic memory and the underlying hippocampal function. However, it remains controversial whether one or two nights of recovery sleep following sleep deprivation fully restores brain and cognitive function. In this study, we used functional magnetic resonance imaging (fMRI) and examined the effects of two consecutive nights (20-hour time-in-bed) of recovery sleep on resting-state hippocampal connectivity and episodic memory deficits following one night of total sleep deprivation (TSD) in 39 healthy adults in a controlled in-laboratory protocol. TSD significantly reduced memory performance in a scene recognition task, impaired hippocampal connectivity to multiple prefrontal and default mode network regions, and disrupted the relationships between memory performance and hippocampal connectivity. Following TSD, two nights of recovery sleep restored hippocampal connectivity to baseline levels, but did not fully restore memory performance nor its associations with hippocampal connectivity. These findings suggest that more than two nights of recovery sleep are needed to fully restore memory function and hippocampal-memory associations after one night of total sleep loss