John Caldwell

Laulima Government Solutions

Previous research has shown greater risk aversion when people make choices about lives than cash. We tested the hypothesis that compared to placebo, exogenous testosterone administration would lead to riskier choices about cash than lives, given testosterone’s association with financial risk-taking and reward sensitivity. A double-blind, placebo-co...

Background Clinical administration of testosterone is widely used due to a variety of claimed physical and cognitive benefits. Testosterone administration is associated with enhanced brain and cognitive function, as well as mood, in energy-balanced males, although such relationships are controversial. However, the effects of testosterone administra...

Background Dietary supplement (DS) use by Army personnel is high and is a safety and readiness issue. Objective Our aim was to examine factors motivating use of DSs among US Army personnel and preferred safety education strategies. Design This mixed-method study used a validated DS questionnaire and subsequent focus groups that were formed based...

The objectives of this study were to quantify the sleep behaviors and alertness of female basketball players and coaches and deploy a sleep education program. Twelve female players and three male coaches wore actigraphy devices for 60 nights during the Women's National Basketball League, Australia, to assess sleep and alertness and completed questi...

The objectives of this study were to quantify the sleep behaviours and alertness of female basketball players and coaches and deploy a sleep education program. Twelve female players and three male coaches wore actigraphy devices for 60 nights during the Women’s National Basketball League, Australia to assess sleep and alertness and completed questi...

BACKGROUND: Caffeine-containing products and dietary supplements are widely used by military populations, but little is known about their use by aviation personnel. This study assessed self-reported sleep, fitness, work-schedules, and caffeine/energy drink use.METHODS: A standardized survey was conducted in person by study personnel using tablet co...

Introduction: Combat sport athletes commonly engage in established and novel acute weight-loss strategies to achieve weight division targets. The effect of such practices on sleep is unknown. Methods: Twenty-two combat sports athletes wore wrist actigraphy devices for nine nights during a training camp and completed questionnaires assessing daytime...

Study Objective Caffeine is the most widely consumed stimulant in the world and sociodemographic factors including occupation are associated with intake. Shift work, required in various occupations, is associated with poor sleep, inadequate diet, and adverse health effects. Using a large nationally-representative database, demographics, sleep, and...

A method for assessing the relative sensitivity of research metrics is proposed and illustrated by comparing 18 outcome measures from a published study of the cognitive, mood, and hormonal effects of four different levels of stress induced by intense military training. Research on the human response to stress often assesses multiple disparate depen...

Sleep is a vital component of preparation, performance and recovery for a Super Rugby game. The purpose of this study was to quantify sleep behaviours and alertness of professional rugby union players during training and a game. Thirty-six rugby union players from a Super Rugby team wore a wrist-activity device (Readiband™) to measure sleep for 3 d...

Background: Severe energy deficits during military operations, produced by significant increases in exercise and limited dietary intake, result in conditions that degrade lean body mass and lower-body muscle function, which may be mediated by concomitant reductions in circulating testosterone. Methods: We conducted a three-phase, proof-of-concep...

Objectives: Caffeine is the most widely consumed stimulant in the world and sociodemographic factors including occupation are associated with its intake. Non-standard work schedules are required in various occupations, and it is difficult to adapt to them. Shift work is associated with poor sleep, inadequate diet and numerous adverse health effect...

Since 2001, the United States (US) has been engaged in the longest and most expensive overseas conflict in its history. Sleep disorders, especially insomnia and obstructive sleep apnea (OSA), are common in service members, and appear related to deployment and combat exposure, but this has not been systematically examined. Therefore, the incidence o...

Fatigue and workplace sleepiness are consequences of modern industrial society. Fatigue is a complex biological phenomenon that occurs as a function of time awake, time-of-day, workload, health, and off-duty lifestyle. Fatigue is a function of two major biological factors – the homeostatic drive for sleep and circadian rhythm of sleepiness. The gre...

The aim of this study was to determine the prevalence of sleep disorders in an elite rugby union team using in-laboratory polysomnography (PSG) and sleep questionnaires. Twenty-five elite rugby union players underwent a night of PSG during the “off season” of the Super Rugby competition. Of interest were measurements that detected the presence of o...

Substantial data on the use of dietary supplements by the general adult population are available, but many population subgroups have not been extensively studied. Because military service members and young people consume large amounts of dietary supplements, including for enhancement of physical performance, weight control, and bodybuilding, which...

Objective: To examine the relationship between regular game-related caffeine consumption on sleep after an evening Super Rugby game. Methods: 20 elite rugby union players wore a wrist-activity monitor to measure sleep for three days before, three days after and on the night of an evening Super Rugby game (19:00-21:00). Players ingested caffeine a...

Accurate measurement of time at lights out is essential for calculation of several measures of sleep in wrist-activity monitors. While some devices use subjective reporting of time of lights out from a sleep diary, others utilise an automated proprietary scoring algorithm to calculate time at lights out, thereby negating the need for a sleep diary....

Background: Wrist-activity monitors (WAM) are used to objectively assess ‘sleep’ in shift-workers. Accurate measurement of time at ‘lights out’ (LO) is essential for calculation of several activity-derived measures including sleep latency (SL), sleep duration (SD), wake after sleep onset (WASO) and sleep efficiency (SE). Some devices use subjective...

Background: The physiological consequences of severe energy deficit include hypogonadism and the loss of fat-free mass. Prolonged energy deficit also impacts physical performance, mood, attentiveness, and decision-making capabilities. This study will determine whether maintaining a eugonadal state during severe, sustained energy deficit attenuates...

Sleep disorders are a critical issue for the military, as they impact operational readiness, personnel health, wellbeing and health-care costs. The incidence of insomnia and obstructive sleep apnea (OSA) are increasing in the United States civilian population, and rates in military personnel exceed those of civilians. Using a comprehensive database...

Objective: This study examined the effects of the removal of electronic devices (i.e., smartphones, etc.) for 48 hours on sleep quality and next-day athletic and cognitive performance in elite Judo athletes. Participants: Over 6 days and nights, 23 eliteAustralian Judo athletes were monitored while attending a camp at the Australian Institute of...

Background: In studies assessing the effects of acute undernutrition on cognitive function, volunteers are sedentary and findings are equivocal, even though glucose concentrations fall substantially. However, military personnel and endurance athletes often are underfed when physical demands, and consequently energy expenditure, are substantial. O...

Caffeine is consumed by over 80% of U.S. adults. This review examines the effects caffeine has on cognitive and physical function, since most real-world activities require complex decision making, motor processing and movement. Caffeine exerts its effects by blocking adenosine receptors. Following low (∼40mg or ∼0.5 mg·kg(-1)) to moderate (∼300mg o...

Stress influences numerous psychological and physiological processes, and its effects have practical implications in a variety of professions and real-world activities.However, few studies have concurrently assessed multiple behavioral, hormonal, nutritional and heart-rate responses of humans to acute, severe stress. This investigation simultaneous...

Purpose: To examine the effects of caffeine use on sleep after a Super Rugby night game (19:00-21:00). Methods: Over 7 consecutive days and nights, 23 elite Rugby Union athletes were monitored before, during and after an evening Super Rugby game. All athletes wore a wrist-based activity monitor (Readiband) to measure their sleep and completed a sle...

Background: Debate regarding the merits of screening pilots for sleep apnea has been stimulated by recently issued guidance from the Federal Aviation Administration. It has long been appreciated that sleep apnea results in poor quality sleep, and that poor quality sleep is associated with daytime fatigue and decrements in performance. However, the...

The book entitled “Managing Sleep and Jet Lag for Optimal Performance” provides a user-friendly overview of the challenges faced by business people and athletes when travelling across multiple time zones. More importantly, the text highlights the scientifically proven techniques for addressing these challenges. At the outset, readers are presented...

Background: Airplane emergency medical services (AEMS) operators use fixed-wing airplanes to undertake rapid response, round-the-clock medical transport missions. This paper explores the structure of long-range, multileg AEMS missions and the sleep and sleepiness of the pilots who work them. Methods: During nine long-range AEMS missions, pilots...

Recent events have highlighted the importance of pilot fatigue in aviation operations. Because of demanding flight schedules, crew members often suffer disrupted sleep and desynchronized circadian rhythms, the combination of which threatens alertness and performance. Unfortunately, market requirements for transcontinental and transoceanic routes, a...

Individual differences in cognitive functioning during extended work hours and shift work are of considerable magnitude, and observed both in the laboratory and in the workplace. These individual differences have a biological basis in trait-like, differential vulnerability to fatigue from sleep loss and circadian misalignment. Trait-like vulnerabil...

This study evaluated oculometrics as a detector of fatigue in Air Force-relevant tasks after sleep deprivation. Using the metrics of total eye closure duration (PERCLOS) and approximate entropy (ApEn), the relation between these eye metrics and fatigue-induced performance decrements was investigated. One damaging effect to the successful outcome of...

Pilot fatigue is a significant problem in modern aviation operations, largely because of the unpredictable work hours, long duty periods, circadian disruptions, and insufficient sleep that are commonplace in both civilian and military flight operations. The full impact of fatigue is often underappreciated, but many of its deleterious effects have l...

This review addresses the problem of fatigue (on-the-job-sleepiness) attributable to sleep loss in modern society and the scientifically proven strategies useful for reducing fatigue-related risks. Fatigue has become pervasive because many people work non-standard schedules, and/or they consistently fail to obtain sufficient sleep. Sleep restrictio...

The present study investigated high workload and time-on-task effects through the assessment of performance and physiological measures during the continuous performance of a complex uninhabited air vehicle UAV task. This study systematically explored the effects of time-on-task, while also incorporating a variety of workload conditions designed to...

Performance-enhancing technologies, specifically psychoactive pharmaceuticals, are currently employed on the battlefield by the militaries of the United States and other western democracies. Ethical arguments exist both for and against the military use of these cogniceuticals. Given the nature of current coalition forces, selection of the most acce...

It has been argued that many subjects may have low awareness of visceral sensations because such feedback is of little relevance and salience in normal activity. This experiment examines awareness of cardiac sensations (heartbeats) in a group of 13 subjects, aged 37–67 yrs, all of whom had myocardial infarcts within the preceding 6 yrs previous to...

Laboratory research has revealed considerable systematic variability in the degree to which individuals' alertness and performance are affected by sleep deprivation. However, little is known about whether or not different populations exhibit similar levels of individual variability. In the present study, we examined individual variability in perfor...

This investigation assessed the impact of ultra-long-range (ULR) simulator flights, departing either in the morning or late evening, on the alertness and performance of 17 commercial aviators. Immediately prior to and throughout each flight, alertness and performance were assessed via a computerized test of sustained attention, subjective questionn...

Fatigue is a well known stressor in aviation operations and its interaction with mental workload needs to be understood. Performance, psychophysiological, and subjective measures were collected during performance of three tasks of increasing complexity. A psychomotor vigilance task, multi-attribute task battery and an uninhabited air vehicle task w...

Introduction Long-haul Commercial Pilots Short-haul Commercial Pilots Military Aviators Sleep Difficulties and Safety Fatigue Countermeasures in Aviation Summary and Conclusions Acknowledgments References

Herein we summarize a discussion on the topic of how psychopharmaceuticals for potential military operational use may be evaluated based on their effects on performance and safety, and introduce two manuscripts: the first (Caldwell and Caldwell; 1) addressing the operational use of fatigue countermeasures; and the second (Rowland; 3) discussing the...

Uncomfortable working and sleeping environments, high operational tempos, sustained operations, and insufficient staffing make fatigue a growing concern. In aviation, where a single mistake can cost millions of dollars, it is essential to optimize operator alertness. Although behavioral and administrative fatigue countermeasures should comprise the...

Recent evidence suggests that underlying patterns of cortical activation may partially account for individual differences in susceptibility to the effects of sleep deprivation. Here, functional magnetic resonance imaging (fMRI) was used to examine the activation of military pilots whose sleep-deprivation vulnerability previously was quantified. A S...

Pilot fatigue is a significant, but often under-reported problem in both civilian and military aviation operations. Although estimates vary, official statistics indicate that fatigue is involved in at least 4–8% of aviation mishaps, and surveys of pilots and aircrew members reveal that fatigue is an important concern throughout today's 24/7 flight...

Fatigue has been identified as an important operational problem in both military and civilian aviation. Requirements for extended duty periods, inconsistent work/rest schedules, multiple-time-zone operations, and night flights combine to potentially degrade performance and alertness in the cockpit. Duty-time limitations traditionally have been reli...

Modafinil is a relatively new alertness-enhancing compound of interest to the military aviation community. Although modafinil has been well-tested in clinical settings, additional studies are required to establish its safety and efficacy for use in pilots. The purpose of this study was to determine whether modafinil (100 mg after 17, 22, and 27 h w...

Fatigue from sleep loss exerts deleterious effects on group performance, and some individuals are more affected than others. Underlying pattern of cortical activation may partially account for such individual differences. The present research utilized fMRI procedures to examine the non-sleep-deprived cortical activation of a group of active-duty mi...

The present study determined whether modafinil (100-mgs after 17, 22, and 27 hours without sleep) attenuated the effects of fatigue on fighter-pilot alertness and performance. A quasi-experimental, single-blind, counterbalanced design was used in which 5 pilots from a previous F-117 fatigue study (in which no fatigue remedy was employed) were retes...

Dextroamphetamine (Dexedrine) is an effective fatigue countermeasure for use in military subject pilots who are deprived of sleep. Anecdotal reports have indicated Dexedrine (Dex) is effective in "real world" sustained operations, and controlled laboratory tests have yielded positive results as well. The aim of this study was to substantiate the ef...

Over the past 30 years, fatigue has contributed to a number of Air Force mishaps. Resource cutbacks combined with increased operational tempos, sustained operations, and night fighting could exacerbate the problem. Extended wakefulness and circadian factors can be especially problematic in military aviation where mission demands sometimes necessita...

Working night shift (reverse cycle) presents problems to personnel due to the difficulty in maintaining alertness during the nighttime hours. When the shift must be worked several consecutive nights, a cumulative sleep debt is created. Appropriate countermeasures are required to help personnel obtain as much sleep as possible so they may perform th...

Sleepiness and fatigue are common in the aviation environment even during peacetime, but during combat, fatigue can reach critical levels due to the necessity for sustained operations and the consequent requirement for lengthy duty schedules. Effective nonpharmacological countermeasures are often difficult to implement in these settings due to the...

This study examined the effects of posture on electroencephalographic (EEG) activity and psychomotor vigilance task (PVT) performance in 16 sleep-deprived volunteers. EEG data were collected while participants completed 10 min PVTs under two counterbalanced sitting/standing conditions during 28 h of continuous wakefulness. In both the sitting and s...

Improperly managed aircrew fatigue can seriously degrade the performance alertness and safety of personnel in the operational environment. Fortunately this danger can be minimized by the use of carefully planned napping strategies. Naps are effective because they are known to reduce the homeostatic drive for sleep. In a variety of settings napping...

Dextroamphetanmine (Dexedrine) is a stimulant capable of temporarily reversing many of the effects of sleep deprivation. This report substantiates the efficacy of Dexedrine for aviation sustained operations. Specifically it is shown that this countermeasure maintains flight skills psychological mood and physiological activation in sleep-deprived pi...

Recently published data on military aviation mishaps suggest aircrew fatigue remains a flight-safety problem. In the current study, a questionnaire was administered to 241 Army aviators and 120 Army enlisted crew members. Inadequate sleep and/or insufficient sleep quality is reportedly adversely affecting on-the-job alertness. The requirements to w...

Background: Recently published data on military aviation mishaps suggest aircrew fatigue remains a flight-safety problem. Methods: In the Current stuck, a questionnaire was administered to 241 Army aviators and 120 Army enlisted crew members. Results: Inadequate sleep and/or insufficient sleep quality is reportedly adversely affecting on-the-job al...

This investigation determined whether the electroencephalographic (EEG) changes associated with sleep deprivation could be reliably recorded from aviators flying standardized maneuvers in an aircraft. In-flight EEG data were recorded from 10 UH-60 helicopter pilots who were kept awake for approximately 26 hr. In addition, resting EEGs and mood data...

Army personnel are commonly rotated to a night shift, or reverse cycle, in order to have the 24-hour period manned at all times. Working reverse cycle presents problems to personnel due to the difficulty in maintaining alertness during the nighttime hours. This is especially difficult when the shift must be worked several consecutive nights, creati...

The present report details the results of a quasi-experimental comparison between the alerting effects of modafinil (Provigil®) and those of dextroamphetamine (Dexedrine®) in sleep-deprived pilots. Data from two separate placebo-controlled studies (one on Dexedrine® and one on Provigil®) were merged and analyzed to determine whether one compound pr...

Because of its effects on productivity and safety, fatigue is receiving increasing attention in a variety of settings, including aviation. Fatigue-related problems cost America an estimated $18 billion a year in terms of lost productivity, and fatigue-related drowsiness on the highways contributes to more than 1500 fatalities, 100,000 crashes, and...

The present investigation was conducted to determine whether the typical EEG changes recorded from subjects in earlier laboratory sleep-deprivation studies would occur under actual in-flight conditions while aviators are piloting an aircraft. In addition, this study was conducted to examine the extent to which fatigue-related deteriorations in flig...

Recently published data on military aviation mishaps suggest aircrew fatigue remains a flight safety problem. The current study, in which the responses from 241 Army aviators and 120 Army enlisted crew members were analyzed, indicates that inadequate sleep and/or insufficient sleep quality is adversely affecting on-the-job alertness. The requiremen...

The comparability of simulator versus aircraft results was examined with a quasi-experimental approach. Flight data from 10 UH-60 pilots, who flew a helicopter simulator, and 10 pilots who flew an aircraft were pooled to assess the influence of the flight platform on Dexedrine(r) versus placebo effects in two 40-hr periods of sustained wakefulness....

In 1998, the FDA approved modafinil for treating excessive daytime sleepiness in narcoleptics, and this has raised questions about the appropriateness of this compound for enhancing alertness in sleep-deprived controls. This study explored the efficacy of modafinil for maintaining the performance of volunteers required to accomplish highly demandin...