Fatigue and alertness in the United States railroad industry part I: the nature of the problem

The railroad industry must actively manage employee fatigue and alertness problems to maintain an optimal level of operational safety and productivity. Given the necessity to operate nights and irregular hours, weekends and holidays under a wide range of physical conditions and service demands, we must explore every reasonable avenue to ensure employees are fit, alert, and well-rested. Effective fatigue management programs must address train crews, dispatchers, signalmen, track workers, and others – both operating and non-operating personnel. Work scheduling is a particular problem in on-call operations because of start-time variability, “call” predictability, and the common use of “shorter-than 24-h work/rest schedules”. Extensive night operations are incompatible with normal circadian rhythms. Staffing limitations often require extensive overtime and reduce the effectiveness of any work schedule. These and other institutional factors significantly contribute to employee sleep deficit and overall fatigue. Lack of alertness and reduced vigilance are related not only to sleep disruption and resulting sleep deficits, but also to cognitive workload, workload transition, the physical working environment, and the design of advanced control systems. Ongoing research into fatigue mitigation and alertness enhancement strategies and into advanced technologies such as Positive Train Control (PTC) can lead to improvements. These include better labor–management agreements, more effective fatigue-related educational programs, improved schedule regularity, and more practical and adaptable federal laws and regulations.     

Sleep, watchkeeping and accidents: a content analysis of incident at sea reports

The unique profession of seafaring involves rest and sleep in a 24-h-a-day work environment that usually involves time-zone crossings, noise, heat, cold and motion. Sleep under such conditions is often difficult to obtain, and sleeping and sleep loss are often related to fatigue and contributory to accidents. This study aims to determine how accident investigators report sleep in Incident at Sea Reports and subsequently analyse the relationships between sleep, fatigue and accidents in these reports.The full text of 44 Incident at Sea Reports was coded and analysed using NUDIST software. This sample included collisions and groundings reported since 1991, where significant human factors contributed to the incident. The Incident at Sea Reports were electronically searched for reference to sleep and content was indexed against parameters such as fatigue behaviours, time of day and contributing personnel. Incident at Sea Reports incorporate three levels of reference to sleep, analysis of which may associate sleeping and sleepiness with accident causation. The highest level of reference unequivocally associates either being asleep, or being sleep deprived with accidents, but not always with fatigue. At an intermediate level, reference to the conflicting pressures of work and sleep on board fishing boats and ships suggests a work environment that is not conducive to obtaining sufficient sleep, and accident investigators are usually unable to link the watchkeeping environment with fatigue as a contributing factor. At the lowest level of association, reference is made to the integrated nature of sleeping and work on board.     

再论心理学的分裂与整合

对心理学分裂危机的忧虑并非杞人忧天,心理学家由于缺乏一个共同的基础而陷入破碎和分裂之中,其它学科的蚕食也对心理学的存在构成威胁。整合并不仅仅是一种良好的愿望,心理学破碎的现实需要实现心理学的整合,大力发展理论心理学,以系统论的科学观为指导是心理学整合的必经之路。     

As we fall asleep we forget about the future: A quantitative linguistic analysis of mentation reports from hypnagogia

We present a quantitative study of mental time travel to the past and future in sleep onset hypnagogia. Three independent, blind judges analysed a total of 150 mentation reports from different intervals prior to and after sleep onset. The linguistic tool for the mentation report analysis grounds on established grammatical and cognitive-semantic theories, and proof of concept has been provided in previous studies. The current results indicate that memory for the future, but not for the past, decreases in sleep onset – thereby supporting preliminary physiological evidence at the level of brain function. While recent memory research emphasizes similarities in the cognitive and physiological processes of mental time travel to the past and future, the current study explores a state of consciousness which may serve to dissociate between the two.     

Motor interference does not impair the memory consolidation of imagined movements

The present study aimed to investigate whether an interference task might impact the sleep-dependent consolidation process of a mentally learned sequence of movements. Thirty-two participants were subjected to a first training session through motor imagery (MI) or physical practice (PP) of a finger sequence learning task. After 2 h, half of the participants were requested to perform a second interfering PP task (reversed finger sequence). All participants were finally re-tested following a night of sleep on the first finger sequence. The main findings revealed delayed performance gains following a night of sleep in the MI group, i.e. the interfering task did not alter the consolidation process, by contrast to the PP group. These results confirm that MI practice might result in less retroactive interference than PP, and further highlight the relevance of the first night of sleep for the consolidation process following MI practice. These data might thus contribute to determine in greater details the practical implications of mental training in motor learning and rehabilitation.     

New parents and driver safety: What’s sleep got to do with it? A systematic review

Fatigue-related motor vehicle crashes are common worldwide and have been addressed by a range of road safety campaigns. These campaigns are typically directed towards at-risk groups (e.g., heavy vehicle drivers), who may be likely to experience fatigue resulting from reduced or disrupted sleep opportunities. Another population likely to experience sleep loss and disruption is new parents. The sleep of new parents is likely to be significantly disrupted by childcare responsibilities. As such, new parents may also be likely to experience fatigue while driving. A systematic review of five databases (PubMed, Cumulative Index to Nursing and Allied Health Literature, PsycINFO, EMBASE, and the Cochrane Central Register of Controlled Trials) was performed to identify what research is currently available on sleep, fatigue, and driving in new parents. A total of twelve documents were included in this review. A synthesis of findings suggests new parents are at risk of fatigued driving – though the amount and quality of evidence available is limited. A research agenda is proposed to address the limitations of this field of research.     

What is the motor vehicle crash risk for drivers with a sleep disorder?

In many parts of the world, drivers with serious sleep disorders have restrictions on their licence – with the fitness-to-drive criteria varying across licensing jurisdictions. This study aimed to systematically review the literature that evaluated the available scientific evidence for the relationship between sleep disorders and two driving safety outcome measures: (i) motor vehicle crashes (MVC) and (ii) on-road driving test outcome. This review was registered with PROSPERO in July 2019 (see CRD42019144643). A systematic search of public health, psychology and transport databases was conducted on November 8th, 2019. The quality of evidence for each study was rated using the National Heart, Lung and Blood Institute Quality Assessment tools. Thirty-nine studies published between 1976 and 2015 met the inclusion criteria (n = 9 case-control; n = 24 cohort/cross-sectional; n = 6 before-after). Overall, the quality of evidence for 22 studies was rated as ‘good’, nine as ‘fair’ and eight as ‘poor’. Included studies addressed: sleep apnoea and sleep-related breathing disorders (n = 35); central disorders of hypersomnolence and narcolepsy (n = 5), and insomnia (n = 2), with some studies covering multiple sleep disorders. Of the thirty-five studies specifically investigating MVC risk associated with sleep apnoea, eighteen studies reported an increased risk (n = 11 ‘good’, n = 4 ‘fair’, n = 3 ‘poor’ quality), seven reported no difference in risk (n = 3 ‘good’, n = 4 ‘fair’ quality), and two provided inconclusive findings (n = 1 ‘good’, n = 1 ‘fair’ quality). Most studies suggested that increased sleep apnoea severity was associated with an increased MVC risk. Furthermore, untreated sleep apnoea was predominantly associated with increased risk, whilst decreased risk was associated with Continuous Positive Airway Pressure (CPAP) and uvulopalatopharyngoplasty (UPPP) treatments. Five studies (n = 3 ‘good’, n = 2 ‘fair’ quality) investigated MVC risk associated with disorders of hypersomnolence and narcolepsy, and all reported increased risk. Only two studies investigated MVC risk associated with insomnia, with inconsistent findings: one reporting increased MVC risk (‘good’) and one reporting no difference (‘fair’). Regarding impacts on on-road driving test outcome, our comprehensive search found no studies investigating the association between sleep disorders and this driving safety outcome measure. Notwithstanding the limitations of the included studies, the weight of evidence suggests a moderately elevated MVC risk for drivers with sleep disorders (sleep apnoea; hypersomnia and narcolepsy), with the majority reporting around two and a half times higher risk, and lower risk with treatment. This evidence is consistent with current fitness-to-drive guidelines, most of which specify licence restrictions conditional upon severity, treatment compliance and effective response to treatment. The generalisability of the findings is limited as many identified studies had methodological limitations, were conducted across a wide time period, in numerous licensing jurisdictions with different requirements, and across a diverse range of participant populations. A large-scale, population-based controlled study, in multiple licensing jurisdictions with equivalent licensing and fitness-to-drive requirements, is warranted to rigorously investigate MVC risk and sleep disorders, including evaluating the possible benefit of therapies.