CONSEQUENCES OF SHIFTWORKING ON SLEEP DURATION,SLEEPINESS, AND SLEEP ATTACKS

Rotating shift and permanent night work arrangements are known to compromise sleep. This study examined the effects of work schedule on sleep duration, excessive sleepiness, sleep attacks, driving, and domestic/professional accidents. A representative sample of the general population of the state of New York—3,345 individuals ≥18 yrs of age—was interviewed by telephone regarding their sleep and psychiatric and organic disorders. Multivariate models were applied to derive odds ratios (OR) after adjustment for age, sex, physical illness, mental disorders, obstructive sleep apnea, and sleep duration. On average (±SE), workers slept 6.7?±?1.5?h, but 40% slept <6.5?h/main sleep episode. Short-sleep duration (<6?h) was strongly associated with fixed night (OR: 1.7) and day-evening-night shiftwork arrangement (OR: 1.9). Some 20% of the workers manifested excessive sleepiness in situations requiring high attention, and it was associated with the fixed night (OR: 3.3) and day-evening-night work arrangements (OR: 1.5). Overall, 5% of the workers reported sleep attacks; however, they occurred three-times more frequently in the fixed night (15.3%) than other work arrangements (OR: 3.2). Driving accidents during the previous 12 months were reported by 3.6% of the workers and were associated with fixed night (OR: 3.9) and day-evening-night (OR: 2.1) work schedules. The findings of this study indicate that working outside the regular daytime hours was strongly associated with shorter sleep duration, sleepiness, and driving accident risk. Night work is the most disrupting, as it is associated with insufficient sleep during the designated rest span and excessive sleepiness and sleep attacks during the span of activity, with an associated consequence being increased driving accident risk. (Author correspondence: mohayon@stanford.edu)     

It is better to be ignorant of our moral enhancement: A reply to Zambrano

In a recent issue of Bioethics, I argued that compulsory moral bioenhancement should be administered covertly. Alexander Zambrano has criticized this argument on two fronts. First, contrary to my claim, Zambrano claims that the prevention of ultimate harm by covert moral bioenhancement fails to meet conditions for permissible liberty-restricting public health interventions. Second, contrary to my claim, Zambrano claims that covert moral bioenhancement undermines autonomy to a greater degree than does overt moral bioenhancement. In this paper, I rebut both of these arguments, then finish by noting important avenues of research that Zambrano’s arguments motivate.     

Power and work produced in different leg muscle groups when rising from a chair

The aim of this study was to determine the power output and work done by different muscle groups at the hip and knee joints during a rising movement, to be able to tell the degree of activation of the muscle groups and the relationship between concentric and eccentric work. Nine healthy male subjects rose from a chair with the seat at knee level. The moments of force about the hip and knee joints were calculated semidynamically. The power output (P) and work in the different muscle groups surrounding the joints was calculated as moment of force times joint angular velocity. Work was calculated as: work = f Pdt. The mean peak concentric power output was for the hip extensors 49.9 W, hip flexors 7.9 W and knee extensor 89.5 W. This power output corresponded to a net concentric work of 20.7 J, 1.0 J and 55.6 J, respectively. There was no concentric power output from the knee flexor muscles. Energy absorption through eccentric muscle action was produced by the hip extensors and hip flexors with a mean peak power output of 4.8 W and 7.4 W, respectively. It was concluded that during rising, the hip and knee muscles mainly worked concentrically and that the greatest power output and work were produced during concentric contraction of the knee and hip extensor muscles. There was however also a demand for eccentric work by the hip extensors as well as both concentric and eccentric work by the hip flexors. The knee flexor muscles were unloaded.     

What is the value of wild animal welfare for restoration ecology?

The restoration community continues to discuss what constitutes good environmental stewardship. One area of tension is the extent to which the well‐being of wild animals should inform restoration efforts. We discuss three ways that the perspective of wild animal welfare can augment restoration ecology: strengthening people's relationship with nature, reinforcing biotic integrity, and reducing mechanistic uncertainty. The animal welfare movement elevates sentient animals as stakeholders and explores how environmental context directly impacts the well‐being of individuals. Viewing wild animals through this lens may encourage people to think and act with empathy and altruism. Second, we incorporate animal welfare into the concept of biotic integrity for ecological and ethical reasons. Restoring ecosystem processes may enhance animal welfare, and vice versa. Alternatively, there may be a trade‐off between these factors, requiring local decision‐makers to prioritize between restoring ecosystem function and promoting individuals' well‐being. We conclude by discussing how welfare can impact population recovery, thereby adding insights about mechanisms underpinning restoration objectives. Ultimately, restoration ecologists and proponents of wild animal welfare could enjoy a productive union.     

Seasonal Variation in Human Salivary Cortisol Concentration

Measurement of cortisol concentration can contribute important information about an individual's ability to adjust to various environmental demands of both physical and psychosocial origin. However, one uncertainty that affects the possibilities of correctly interpreting and designing field studies is the lack of observations of the impact of seasonal changes on cortisol excretion. For this reason, the month‐to‐month changes in diurnal cortisol concentration, the awakening cortisol response (ACR), maximum morning concentration, and fall during the day were studied in a group of 24 healthy men and women 32 to 61 yrs of age engaged in active work. On one workday for 12 consecutive months, participants collected saliva at four time points for determination of cortisol: at awakening, +30 min, +8 h, and at 21:00 h. Data were analyzed by a repeated measures design with month (12 levels) and time‐of‐day (4 levels) as categorical predictors. Cortisol concentrations were analyzed on a log scale. The diurnal pattern of cortisol was similar across months (interaction between month and time of day: p>0.4). The main effects of month and time‐of‐day were statistically significant (p <0.001). Highest concentrations were observed in February, March, and April, and lowest concentrations were observed in July and August. There were no statistically significant effects in any of the other measures, or between men and women. In conclusion, a seasonal variation in salivary cortisol concentrations was detected in an occupationally active population. Thus, seasonal variation needs to be taken into account when designing and evaluating field studies and interventions and when making comparisons across studies.     

Sleep,Sleepiness, Fatigue,and Performance of 12-Hour-Shift Nurses

Nurses working 12-h shifts complain of fatigue and insufficient/poor-quality sleep. Objectively measured sleep times have not been often reported. This study describes sleep, sleepiness, fatigue, and neurobehavioral performance over three consecutive 12-h (day and night) shifts for hospital registered nurses. Sleep (actigraphy), sleepiness (Karolinska Sleepiness Scale [KSS]), and vigilance (Performance Vigilance Task [PVT]), were measured serially in 80 registered nurses (RNs). Occupational fatigue (Occupational Fatigue Exhaustion Recovery Scale [OFER]) was assessed at baseline. Sleep was short (mean 5.5?h) between shifts, with little difference between day shift (5.7?h) and night shift (5.4?h). Sleepiness scores were low overall (3 on a 1–9 scale, with higher score indicating greater sleepiness), with 45% of nurses having high level of sleepiness (score ?>?7) on at least one shift. Nurses were progressively sleepier each shift, and night nurses were sleepier toward the end of the shift compared to the beginning. There was extensive caffeine use, presumably to preserve or improve alertness. Fatigue was high in one-third of nurses, with intershift fatigue (not feeling recovered from previous shift at the start of the next shift) being most prominent. There were no statistically significant differences in mean reaction time between day/night shift, consecutive work shift, and time into shift. Lapsing was traitlike, with rare (39% of sample), moderate (53%), and frequent (8%) lapsers. Nurses accrue a considerable sleep debt while working successive 12-h shifts with accompanying fatigue and sleepiness. Certain nurses appear more vulnerable to sleep loss than others, as measured by attention lapses. (Author correspondence: jgeiger@son.umaryland.edu)     

Working on Sundays–Effects on Safety,Health, and Work-life Balance

Several attributes of the work schedule can increase the risk of occupational injuries and accidents, health impairments, and reduced social participation. Although previous studies mainly focused on the effects of shiftwork and long working hours on employee health and safety, there is little evidence of a potential negative impact of working Sundays on the incidence of occupational accidents, health impairments, and work-life balance. A representative sample of employed workers in 31 member and associated states of the European Union (n?=?23,934) served as the database for a cross-sectional analysis. The sample was collected via face-to-face interviews in the year 2005. The association of the risks of occupational accidents, health impairments, and decreases in work-life balance with working Sundays was calculated using logistic regression models, controlling for potential confounders, such as shiftwork, workload, and demographic characteristics. The results indicated that working one or more Sundays/month was associated with increase both in the risk of reporting one or more health impairments (odds ratio [OR]: 1.17, 95% confidence interval [CI]: 1.06–1.29) and poorer work-life balance (OR: 1.15, 95% CI: 1.02–1.28). These effects remained after controlling for potentially confounding factors, such as other work schedule attributes, intensity of physical and mental workload, and individual characteristics. Furthermore, working Sundays was also related to increased risk of occupational accidents within the last year (OR: 1.34, 95% CI: 1.03–1.73). Controlling again for individual, workload, and working-time characteristics, a significant association with accident risk, however, remained only in work sectors with low a priori risk of occupational accidents (OR: 1.40, 95% CI: 1.02–1.91), although the increased risk could be observed for both medium and high a priori risk sectors working Sundays (without controlling for additional confounders). The results thus indicate that the detrimental effects of working Sundays on safety, health, and social well-being should be taken into account when designing work schedules. The potential hazards to employees' safety, health, and work-life balance, in particular, should be considered in discussions concerning extending work on Sundays in certain sectors, e.g., retail. (Author correspondence: awirtz@hsph.harvard.edu)     

Factors Affecting Work Ability in Day and Shift‐Working Nurses

Satisfactory work ability is sustained and promoted by good physical and mental health and by favorable working conditions. This study examined whether favorable and rewarding work‐related factors increased the work ability among European nurses. The study sample was drawn from the Nurses' Early Exit Study and consisted of 7,516 nursing staff from seven European countries working in state‐owned and private hospitals. In all, 10.8% were day, 4.2% were permanent night, 20.9% were shift without night shift, and 64.1% were shift workers with night shifts. Participants were administered a composite questionnaire at baseline (Time 0) and 1 yr later (Time 1). The Work Ability Index (WAI) at Time 1 was used as the outcome measure, while work schedule, sleep, rewards (esteem and career), satisfaction with pay, work involvement and motivation, and satisfaction with working hours at Time 0 were included as potential determinants of work ability. Univariate and multivariate analyses were conducted after adjusting for a number of confounders (i.e., country, age, sex, type of employment, family status, and other job opportunities in the same area). Work schedule was not related to Time 1 changes in WAI. Higher sleep quality and quantity and more favorable psychosocial factors significantly increased work ability levels. Higher sleep quality and quantity did not mediate the effect of work schedule on work ability. No relevant interaction effects on work ability were observed between work schedule and the other factors considered at Time 0. As a whole, sleep and satisfaction with working time were gradually reduced from day work to permanent night work. However, scores on work involvement, motivation, and satisfaction with pay and rewards were the highest in permanent night workers and the lowest in rotating shift workers that included night shifts.     

Independent Effects of Sleep Duration and Body Mass Index on the Risk of a Work-Related Injury: Evidence From the US National Health Interview Survey (2004–2010)

Fatigue has been linked to adverse safety outcomes, and poor quality or decreased sleep has been associated with obesity (higher body mass index, BMI). Additionally, higher BMI is related to an increased risk for injury; however, it is unclear whether BMI modifies the effect of short sleep or has an independent effect on work-related injury risk. To answer this question, the authors examined the risk of a work-related injury as a function of total daily sleep time and BMI using the US National Health Interview Survey (NHIS). The NHIS is an in-person household survey using a multistage, stratified, clustered sample design representing the US civilian population. Data were pooled for the 7-yr survey period from 2004 to 2010 for 101 891 “employed” adult subjects (51.7%; 41.1?±?yrs of age [mean?±?SEM]) with data on both sleep and BMI. Weighted annualized work-related injury rates were estimated across a priori defined categories of BMI: healthy weight (BMI: <25), overweight (BMI: 25–29.99), and obese (BMI: ≥30) and also categories of usual daily sleep duration: <6, 6–6.99, 7–7.99, 8–8.99, and ≥9?h. To account for the complex sampling design, including stratification, clustering, and unequal weighting, weighted multiple logistic regression was used to estimate the risk of a work-related injury. The initial model examined the interaction among daily sleep duration and BMI, controlling for weekly working hours, age, sex, race/ethnicity, education, type of pay, industry, and occupation. No significant interaction was found between usual daily sleep duration and BMI (p?=?.72); thus, the interaction term of the final logistic model included these two variables as independent predictors of injury, along with the aforementioned covariates. Statistically significant covariates (p?≤?.05) included age, sex, weekly work hours, occupation, and if the worker was paid hourly. The lowest categories of usual sleep duration (<6 and 6–6.9?h) showed significantly (p?≤?.05) elevated injury risks than the referent category (7–8?h sleep), whereas sleeping >7–8?h did not significantly elevate risk. The adjusted injury risk odds ratio (OR) for a worker with a usual daily sleep of <6?h was 1.86 (95% confidence interval [CI]: 1.37–2.52), and for 6–6.9?h it was 1.46 (95% CI: 1.18–1.80). With regards to BMI, the adjusted injury risk OR comparing workers who were obese (BMI: ≥30) to healthy weight workers (BMI: <25) was 1.34 (95% CI: 1.09–1.66), whereas the risk in comparing overweight workers (BMI: 25–29.99) to healthy weight risk was elevated, but not statistically significant (OR?=?1.08; 95% CI: .88–1.33). These results from a large representative sample of US workers suggest increase in work-related injury risk for reduced sleep regardless of worker's body mass. However, being an overweight worker also increases work-injury risk regardless of usual daily sleep duration. The independent additive risk of these factors on work-related injury suggests a substantial, but at least partially preventable, risk. (Author correspondence: david.lombardi@libertymutual.com)     

The relative contributions of sagittal,frontal, and transverse joint works to self-paced incline and decline slope walking

Positive and negative work are generated at the lower limb joints in order to locomote over various terrains. Joint work quantifies the changes in energy that are necessary to adapt gait to environmental demands. The aim of this study was to quantify 3D joint work at the hip, knee, and ankle during slope walking. Work was calculated for ten males (23.9 ± 1.1 years) walking at a self-selected speed on inclines and declines (−20, −12, −6, 0, 6, 12, 20 degrees). Sagittal positive work significantly increased at the hip, knee, and ankle for incline walking (for example, hip positive work increased 153%, 280%, and 453% for 6, 12, and 20 degrees, respectively; knee and ankle positive work also increased) (p ≤ 0.05), in order to raise and propel the body forward. Sagittal negative work increased significantly at the hip, knee and ankle for decline walking (for example, knee negative work increased 193%, 355%, and 496% for −6, −12, and −20 degrees, respectively; hip and ankle negative work also increased) (p ≤ 0.05), in order to control body descent. These substantial changes in work will be especially challenging for people with compromised strength due to age and disease. Furthermore, changes in work were not limited to the sagittal plane: 46% of the total hip joint work occurred in the frontal and transverse planes for six degree decline walking. Thus, decline walking placed greater demands on the hip ab/adductors and rotators, and this may be related to the greater risk of falls observed for descent versus ascent.