Mild hypohydration increases the frequency of driver errors during a prolonged, monotonous driving task

The aim of the present study was to examine the effect of mild hypohydration on performance during a prolonged, monotonous driving task. Methods: Eleven healthy males (age 22 ± 4 y) were instructed to consume a volume of fluid in line with published guidelines (HYD trial) or 25% of this intake (FR trial) in a crossover manner. Participants came to the laboratory the following morning after an overnight fast. One hour following a standard breakfast, a 120 min driving simulation task began. Driver errors, including instances of lane drifting or late breaking, EEG and heart rate were recorded throughout the driving task. Results: Pre-trial bodymass (P=0.692), urine osmolality (P=0.838) and serumosmolality (P=0.574)were the same on both trials. FR resulted in a 1.1±0.7% reduction in bodymass, compared to−0.1±0.6% in the HYD trial (P = 0.002). Urine and serum osmolality were both increased following FR (P b 0.05). There was a progressive increase in the total number of driver errors observed during both the HYD and FR trials, but significantly more incidents were recorded throughout the FR trial (HYD 47 ± 44, FR 101 ± 84; ES = 0.81; P = 0.006). Conclusions: The results of the present study suggest that mild hypohydration, produced a significant increase in minor driving errors during a prolonged, monotonous drive, compared to that observed while performing the same task in a hydrated condition. The magnitude of decrement reported,was similar to that observed following the ingestion of an alcoholic beverage resulting in a blood alcohol content of approximately 0.08% (the current UK legal driving limit), or while sleep deprived

Review of the literature on coffee stops as a road safety measure

Caffeine is a widely available mild stimulant thought to promote alertness. It has been suggested that the consumption of caffeine could be promoted at designated ‘coffee stops’ by the side of the road in rest areas. However, there is some concern that coffee stops might encourage driving when a driver should be resting. Although such roadside initiatives have been operating in Australia and overseas for many years, there are few quantitative evaluations examining the road safety benefits of such programs. Based on empirical research evidence, there is some support for the provision of coffee at roadside rest stops to temporarily alleviate fatigue when driving. However, the combination of drinking caffeine (approximately two cups of coffee) and napping (i.e., 15 minutes) during a break appears to be more beneficial than caffeine alone. Therefore, to enhance the beneficial effects of coffee stops, drivers feeling fatigued should be encouraged to take a 10 to 15 minute nap and to consume coffee. However, even though caffeine has a beneficial effect in alleviating fatigue, these effects are only temporary, lasting for about two hours. Consequently, caffeine alone should not be promoted as a substitute for sleep.LN Wundersitz, MRJ Baldoc

Effects of circadian rhythm phase alteration on physiological and psychological variables: Implications to pilot performance (including a partially annotated bibliography)

The effects of environmental synchronizers upon circadian rhythmic stability in man and the deleterious alterations in performance and which result from changes in this stability are points of interest in a review of selected literature published between 1972 and 1980. A total of 2,084 references relevant to pilot performance and circadian phase alteration are cited and arranged in the following categories: (1) human performance, with focus on the effects of sleep loss or disturbance and fatigue; (2) phase shift in which ground based light/dark alteration and transmeridian flight studies are discussed; (3) shiftwork; (4)internal desynchronization which includes the effect of evironmental factors on rhythmic stability, and of rhythm disturbances on sleep and psychopathology; (5) chronotherapy, the application of methods to ameliorate desynchronization symptomatology; and (6) biorythm theory, in which the birthdate based biorythm method for predicting aircraft accident susceptability is critically analyzed. Annotations are provided for most citations

Distal Cooling and Sustained Attention

Introduction: Vigilance is directly related to core and skin temperatures (TC and Tsk). Biological day reflects a high TC and alertness; night reflects vice versa. At rest, TC is regulated largely by controlling blood flow (and hence Tsk) in extremities; their vasodilation strongly predicts reduced vigilance (Raymann et al., 2007b) and faster sleep onset (Kräuchi et al., 1999). In narcolepsy, high daytime extremity temperatures and a smaller distal-to-proximal gradient (DPG) indicates higher sleep propensity (Fronczek et al., 2006b). Cool extremities have been linked observationally to delayed sleep onset in the elderly, and experimentally shown to reduce sleep propensity in narcolepsy (Fronczek et al., 2008). Therefore, the aim of this study was to test the hypothesis that cooling the feet would maintain vigilance during extended wakefulness in healthy adults. Methods: A randomised cross-over experiment was completed using nine healthy young adult participants with normal sleep patterns. After providing informed consent, and a daytime familiarisation, they undertook three 4-h laboratory sessions in which water-perfused booties were used to provide Mild cooling, Moderate cooling or no cooling (Control). Sessions were in a dimly-lit room, beginning at 2230. Each 30 min consisted of quiet rest interspersed with a 10- min psychomotor vigilance task (PVT), 7-min Karolinska Drowsiness Test (KDT), and ratings of sleepiness, perceived body temperature and thermal discomfort. EEG spectral powers (theta, alpha and beta) were determined within the PVT and KDT. Analyses were by repeated measures ANOVA (α=0.05) with post-hoc contrasts. Results: Foot temperatures in Control and Mild and Moderate cooling averaged 34.5 ±0.5, 30.8±0.2 and 26.4 ±0.1 OC (all P0.80). Participants felt cooler throughout both cooling trials, but thermal comfort was unaffected (P=0.43), as were almost all EEG parameters during the KDT. All dependent measures were affected by time. Discussion and Conclusion: In healthy, young adults, core temperature and vigilance decline during the period of normal sleep onset and early sleep regardless of mild or moderate cooling of the feet, and any effect on sleepiness is small and transient

Coffee and Caffeine Consumption for Human Health

The year 2019 has been prolific in terms of new evidence regarding the effects of coffee and caffeine consumption on diverse aspects of human functioning. This book collects 20 high-quality manuscripts published in Nutrients that include original investigation or systematic review studies of the effects of caffeine intake on human performance and health. The diversity of the articles published in this Special Issue highlights the extent of the effects of coffee and caffeine on human functioning, while underpinning the positive nature of most of these effects. This book will help with understanding why the natural sources of caffeine are so widely present in the nutrition behaviors of modern society

Fatigue Identification and Management in Flight Training: An Investigation of Collegiate Aviation Pilots

Objective: The purpose of this study was to evaluate collegiate aviation students’ self-awareness of their fatigue issues; to investigate possible causes of fatigue afflicting collegiate aviation students; and to investigate the collegiate aviation students’ lifestyle and perceptions of personal solutions to fatigue. Background: Pilot fatigue is a significant safety hazard in aviation operations. Several factors can contribute to fatigue, including inadequate sleep, long work hours, and inadequate nutritional habits. Some factors, such as social and academic activities, could be unique for Title 14 Code of Federal Regulations (CFR) Part 141 collegiate aviation pilots. Previous studies have addressed fatigue in commercial and military aviation. However, few studies have targeted collegiate aviation students. Method: An online survey questionnaire was utilized to investigate collegiate aviation students’ self-awareness of their fatigue issues; the possible causes of fatigue afflicting those students; their lifestyle as well as their perceptions of personal solutions to fatigue. The population for this study consisted of a subset of the GA community, flight instructors and students from an accredited 14 CFR Part 141 four-year degree-awarding university in the Midwestern region of the United States. Additionally, participants were recruited from a local fixed based operator. Results: Findings indicated that fatigue has played a role during flight training. Pilots had, for example overlooked mistakes because of fatigue. Responses also suggested decrements in alertness and cognitive functions as a result of fatigue. Conclusion: Fatigue is a safety hazard in a collegiate environment that needs addressing. Systematic fatigue education and training, better lifestyle practices, effective workload management, and even a prescriptive approach could significantly enhance aviation safety and the well-being of student pilots