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

Light as a chronobiologic countermeasure for long-duration space operations

Long-duration space missions require adaptation to work-rest schedules which are substantially shifted with respect to earth. Astronauts are expected to work in two-shift operations and the environmental synchronizers (zeitgebers) in a spacecraft differ significantly from those on earth. A study on circadian rhythms, sleep, and performance was conducted by exposing four subjects to 6 deg head-down tilt bedrest (to simulate the effects of the weightless condition) and imposing a 12-h shift (6 h delay per day for two days). Bright light was tested in a cross-over design as a countermeasure for achieving faster resynchronization and regaining stable conditions for sleep and circadian rhythmicity. Data collection included objective sleep recording, temperature, heart rate, and excretion of hormones and electrolytes as well as performance and responses to questionnaires. Even without a shift in the sleep-wake cycle, the sleep quantity, circadian amplitudes and 24 h means decreased in many functions under bedrest conditions. During the shift days, sleepiness and fatigue increased, and alertness decreased. However, sleep quantity was regained, and resynchronization was completed within seven days after the shift for almost all functions, irrespective of whether light was administered during day-time or night-time hours. The time of day of light exposure surprisingly appeared not to have a discriminatory effect on the resynchronization speed under shift and bedrest conditions. The results indicate that simulated weightlessness alters circadian rhythms and sleep, and that schedule changes induce additional physiological disruption with decreased subjective alertness and increased fatigue. Because of their operational implications, these phenomena deserve additional investigation

Crew Factors in Flight Operations 7: Psychophysiological Responses to Overnight Cargo Operations

To document the psychophysiological effects of flying overnight cargo operations, 41 B-727 crew members (average age 38 yr) were monitored before, during, and after one of two typical 8-day trip patterns. During daytime layovers, the average sleep episode was 3 hr (41%) shorter than nighttime sleeps and was rated as lighter, less restorative, and poorer overall. Sleep was frequently split into several episodes and totaled 1.2 hr less per 24 hr than on pretrip days. Each trip pattern included a night off, which was an effective countermeasure against the accumulating sleep debt. The organization of sleep during daytime layovers reflected the interaction of duty timing with circadian physiology. The circadian temperature rhythm did not adapt completely to the inverted wake-rest schedule on duty days, being delayed by about 3 hr. Highest subjective fatigue and lowest activation occurred around the time of the temperature minimum. On duty days, reports of headaches increased by 400%, of congested nose by 200%, and of burning eyes by 900%. Crew members also reported eating more snacks. Compared with daytime short-haul air-transport operations, the overnight cargo trips included fewer duty and flight hours, and had longer layovers. Overnight cargo crews also averaged 5.4 yr younger than their daytime short-haul counterparts. On trips, both groups lost a comparable amount of sleep per 24 hr, but the overnight cargo crews had shorter individual sleep episodes and more broken sleep. These data clearly demonstrate that overnight cargo operations, like other night work, involve physiological disruption not found in comparable daytime operations

Crew factors in flight operations 6: Psychophysiological responses to helicopter operations

Thirty-two helicopter pilots were studied before, during, and after 4-5 day trips providing support services from Aberdeen, Scotland, to rigs in the North Sea oil fields. Early on-duty times obliged subjects to wake up 1.5 hours earlier on trip days than on pretrip days. Consequently, they slept nearly an hour less per night on trips. They reported more fatigue on post-trip days than on pretrip days, suggesting a cumulative effect of duty-related activities and sleep loss. Fatigue and negative affect were higher, and activation lower, by the end of trip days than by the end of pretrip days. The earlier a subject went on duty, the lower his activation by the end of the day. Caffeine consumption increased 42 percent on trip days. The incidence of headache doubled, of back pain increased twelve fold, and of burning eyes quadrupled. In the aircraft studied, thermal discomfort and high vibration levels were common. The longer pilots remained on duty, the more negative their mood became

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

Crew factors in flight operations. 8: Factors influencing sleep timing and subjective sleep quality in commercial long-haul flight crews

How flight crews organize their sleep during layovers on long-haul trips is documented. Additionally, environmental and physiological constraints on sleep are examined. In the trips studied, duty periods averaging 10.3 hr alternated with layovers averaging 24.8 hr, which typically included two subject-defined sleep episodes. The circadian system had a greater influence on the timing and duration of first-sleeps than second-sleeps. There was also a preference for sleeping during the local night. The time of falling asleep for second-sleeps was related primarily to the amount of sleep already obtained in the layover, and their duration depended on the amount of time remaining in the layover. For both first- and second-sleeps, sleep durations were longer when subjects fell asleep earlier with respect to the minimum of the circadian temperature cycle. Naps reported during layovers and on the flight deck may be a useful strategy for reducing cumulative sleep loss. The circadian system was not able to synchronize with the rapid series of time-zone shifts. The sleep/wake cycle was forced to adopt a period different from that of the circadian system. Flight and duty time regulations are a means of ensuring that reasonable minimum rest periods are provided. This study clearly documents that there are physiologically and environmentally determined preferred sleep times within a layover. The actual time available for sleep is thus less than the scheduled rest period

Crew factors in flight operations 2: Psychophysiological responses to short-haul air transport operations

Seventy-four pilots were monitored before, during, and after 3- or 4-day commercial short-haul trip patterns. The trips studied averaged 10.6 hr of duty per day with 4.5 hr of flight time and 5.5 flight segments. The mean rest period lasted 12.5 hr and occurred progressively earlier across successive days. On trip nights, subjects took longer to fall asleep, slept less, woke earlier, and reported lighter, poorer sleep with more awakenings than on pretrip nights. During layovers, subjective fatigue and negative affect were higher, and positive affect and activation lower, than during pretrip, in-flight, or posttrip. Pilots consumed more caffeine, alcohol, and snacks on trip days than either pretrip or posttrip. Increases in heart rate over mid-cruise were observed during descent and landing, and were greater for the pilot flying. Heart-rate increases were greater during takeoff and descent under instrument meteorological conditions (IMC) than under visual meteorological conditions (VMC). The following would be expected to reduce fatigue in short-haul operations: regulating duty hours, as well as flight hours; scheduling rest periods to begin at the same time of day, or progressively later, across the days of a trip; and educating pilots about alternatives to alcohol as a means of relaxing before sleep

Integrative analysis of the microbiome and metabolome of the human intestinal mucosal surface reveals exquisite inter-relationships

Background: Consistent compositional shifts in the gut microbiota are observed in IBD and other chronic intestinal disorders and may contribute to pathogenesis. The identities of microbial biomolecular mechanisms and metabolic products responsible for disease phenotypes remain to be determined, as do the means by which such microbial functions may be therapeutically modified. Results: The composition of the microbiota and metabolites in gut microbiome samples in 47 subjects were determined. Samples were obtained by endoscopic mucosal lavage from the cecum and sigmoid colon regions, and each sample was sequenced using the 16S rRNA gene V4 region (Illumina-HiSeq 2000 platform) and assessed by UPLC mass spectroscopy. Spearman correlations were used to identify widespread, statistically significant microbial-metabolite relationships. Metagenomes for identified microbial OTUs were imputed using PICRUSt, and KEGG metabolic pathway modules for imputed genes were assigned using HUMAnN. The resulting metabolic pathway abundances were mostly concordant with metabolite data. Analysis of the metabolome-driven distribution of OTU phylogeny and function revealed clusters of clades that were both metabolically and metagenomically similar. Conclusions: The results suggest that microbes are syntropic with mucosal metabolome composition and therefore may be the source of and/or dependent upon gut epithelial metabolites. The consistent relationship between inferred metagenomic function and assayed metabolites suggests that metagenomic composition is predictive to a reasonable degree of microbial community metabolite pools. The finding that certain metabolites strongly correlate with microbial community structure raises the possibility of targeting metabolites for monitoring and/or therapeutically manipulating microbial community function in IBD and other chronic diseases

Multi-omics of the gut microbial ecosystem in inflammatory bowel diseases.

Inflammatory bowel diseases, which include Crohn's disease and ulcerative colitis, affect several million individuals worldwide. Crohn's disease and ulcerative colitis are complex diseases that are heterogeneous at the clinical, immunological, molecular, genetic, and microbial levels. Individual contributing factors have been the focus of extensive research. As part of the Integrative Human Microbiome Project (HMP2 or iHMP), we followed 132 subjects for one year each to generate integrated longitudinal molecular profiles of host and microbial activity during disease (up to 24 time points each; in total 2,965 stool, biopsy, and blood specimens). Here we present the results, which provide a comprehensive view of functional dysbiosis in the gut microbiome during inflammatory bowel disease activity. We demonstrate a characteristic increase in facultative anaerobes at the expense of obligate anaerobes, as well as molecular disruptions in microbial transcription (for example, among clostridia), metabolite pools (acylcarnitines, bile acids, and short-chain fatty acids), and levels of antibodies in host serum. Periods of disease activity were also marked by increases in temporal variability, with characteristic taxonomic, functional, and biochemical shifts. Finally, integrative analysis identified microbial, biochemical, and host factors central to this dysregulation. The study's infrastructure resources, results, and data, which are available through the Inflammatory Bowel Disease Multi'omics Database ( http://ibdmdb.org ), provide the most comprehensive description to date of host and microbial activities in inflammatory bowel diseases

Alternative organizing in times of crisis : resistance assemblages and socio-spatial solidarity

This paper draws on research conducted in Greece, where, during the last seven years, an acute socio-economic crisis has led to the emergence of a number of alternative organizational forms. By foregrounding the term drasis, the unexpected unfolding of an event in a specific space and time, we discuss how these alternative forms assemble differential capacities in order to resist the neoliberal ordering of socio-spatial and economic relations. In particular, we focus on two self-organized spaces, namely, a social centre and a squatted public garden and discuss two concrete instances of drasis. We propose that drasis instigates the establishment and evolution of transformative, prefigurative organizing through three interrelated processes, namely, the formation of resistance assemblages, social learning and socio-spatial solidarity. The paper offers three propositions, suggesting that drasis provides the socio-material conditions through which new resistance formations challenge the established productive forces of society and co-produce alternative forms of civic life.© 2017 published by SAGE. This is an author produced version of a paper published in European Urban and Regional Studies, uploaded in accordance with the publisher’s self- archiving policy. The final published version (version of record) is available online at http://journals.sagepub.com/doi/10.1177/0969776416683001. Some minor differences between this version and the final published version may remain. We suggest you refer to the final published version should you wish to cite from it