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Objectives: The aim of this study was to examine whether changes in work shifts and shift intensity are related to changes in difficulties to fall asleep, fatigue, and sleep length. Methods: Questionnaire responses of hospital employees (N=7727, 93% women) in 2008, 2012, 2014 and 2015 were linked to daily-based records of working hours during three months preceding each survey. We used conditional logistic regression and longitudinal fixed-effects analyses to investigate odds ratios (OR) and 95% confidence intervals (CI) for each 25% within-individual change in the proportion of working hour characteristics in relation to changes in fatigue, difficulties to fall asleep, and 24-hour sleep length. Results: Change in night but not in morning or evening shifts was associated with parallel changes in odds for longer sleep length (OR 1.45, 95% CI 1.28-1.64) and fatigue during free days (OR 1.38, 95% CI 1.16-1.64). Similarly, short shift intervals and having ＞2 but not ＞4 consecutive night shifts were associated with increased odds of fatigue during work and difficulties to fall asleep (OR 1.42, 95% CI 1.19-1.72 and OR 1.10, 95% CI 1.05-1.19, respectively). Among workers aged ≥50 years, the associations were the strongest between night shifts and longer sleep (OR 2.24, 95% CI 1.52-3.81) and between higher proportion of short shift intervals and fatigue during free days (OR 1.68, 95% CI 1.10-2.54). Conclusions: Among shift workers with fatigue or sleep problems, decreasing the proportion of night shifts and quick returns and giving preference to quickly forward-rotating shift systems may reduce fatigue.

Background Shift work can disturb circadian homeostasis and result in fatigue, excessive sleepiness, and reduced quality of life. Light therapy has been shown to impart positive effects in night shift workers. We sought to determine whether or not prolonged exposure to bright light during a night shift reduces sleepiness and enhances psychomotor performance among ICU nurses. Methods This is a single-center randomized, crossover clinical trial at a surgical trauma ICU. ICU nurses working a night shift were exposed to a 10-h period of high illuminance (1500–2000 lx) white light compared to standard ambient fluorescent lighting of the hospital. They then completed the Stanford Sleepiness Scale and the Psychomotor Vigilance Test. The primary and secondary endpoints were analyzed using the paired t test. A p  value <0.05 was considered significant. Results A total of 43 matched pairs completed both lighting exposures and were analyzed. When exposed to high illuminance lighting subjects experienced reduced sleepiness scores on the Stanford Sleepiness Scale than when exposed to standard hospital lighting: mean (sem) 2.6 (0.2) vs. 3.0 (0.2), p  = 0.03. However, they committed more psychomotor errors: 2.3 (0.2) vs. 1.7 (0.2), p  = 0.03. Conclusions A bright lighting environment for ICU nurses working the night shift reduces sleepiness but increases the number of psychomotor errors. Trial registration ClinicalTrials.gov, NCT03331822 . Retrospectively registered on 6 November 2017.

Objectives This discussion paper aims to provide scientifically based recommendations on night shift schedules, including consecutive shifts, shift intervals and duration of shifts, which may reduce health and safety risks. Short-term physiological effects in terms of circadian disruption, inadequate sleep duration and quality, and fatigue were considered as possible links between night shift work and selected health and safety risks, namely, cancer, cardio-metabolic disease, injuries, and pregnancy-related outcomes. Method In early 2020, 15 experienced shift work researchers participated in a workshop where they identified relevant scientific literature within their main research area. Results Knowledge gaps and possible recommendations were discussed based on the current evidence. The consensus was that schedules which reduce circadian disruption may reduce cancer risk, particularly for breast cancer, and schedules that optimize sleep and reduce fatigue may reduce the occurrence of injuries. This is generally achieved with fewer consecutive night shifts, sufficient shift intervals, and shorter night shift duration. Conclusions Based on the limited, existing literature, we recommend that in order to reduce the risk of injuries and possibly breast cancer, night shift schedules have: (i) ≤3 consecutive night shifts; (ii) shift intervals of ≥11 hours; and (iii) ≤9 hours shift duration. In special cases - eg, oil rigs and other isolated workplaces with better possibilities to adapt to daytime sleep - additional or other recommendations may apply. Finally, to reduce risk of miscarriage, pregnant women should not work more than one night shift in a week.

Objectives Unhealthy dietary profiles contribute to the elevated risk of chronic diseases for shift workers. There has been limited investigation into factors associated both with shift work and diet, such as sleep and mood, that may further influence food intake among shift workers. The aim of this study was to explore the relationship between shift work, sleep, mood, and diet. Methods Shift working nurses [N=52; 46 female; age: mean 39.8 (SD 12.4) years] participated in a 14-day, repeated measures, within- and between-subjects design study. Analyses included data from 40 nurses over 181 shifts. Food diaries were completed for a minimum of three days per shift type (morning, afternoon, night). Foodworks nutrition software was used to determine energy intake in kilojoules and macronutrient intake (as a percentage of total energy intake). Mood (happiness, anxiety, depressive mood, stress, and tiredness) was measured using visual analog scales. Sleep was estimated using actigraphy. Demographic and work-related variables (covariates) were measured using a modified version of the Standard Shiftwork Index. A path analysis was conducted using generalized structural equation modelling with a random effect of participant ID. Predictors were selected using purposive selection of covariates (an alternative to stepwise modelling) and final models included important predictors only. Results Compared to night and morning shifts, results showed that working an afternoon shift was associated with a lower energy intake (β= -1659.4, P<0.01) and lower levels of stress (β= -5.6, P<0.01). Higher levels of stress were associated with a higher energy intake (β=35.3, P<0.01) and a higher percentage of fat (ß=0.1, P=0.05) and saturated fat (β=0.1, P<0.01). Compared to the other shift types, morning shift was associated with lower carbohydrates (β= -4.3, P<0.01) and night shift was associated with lower protein (β= -2.7, P=0.03). Lower sleep efficiency was associated with a higher carbohydrate intake (β= -0.4, P<0.01) and a lower protein intake (β=0.25, P<0.01) Conclusions Results suggest that compared to nights and mornings, afternoon shifts were associated with reduced energy consumption. Negative mood (stress, depression, and anxiety) mediated the association between shift type and energy intake. Negative mood was also associated with higher fat intake. Dietary interventions for shift workers should consider the role of mood as well as shift type.

OBJECTIVES: This study investigated the associations between shift work characteristics and self-reported work-related accidents as well as incidents of dozing off at work and during the work commute. METHODS: Data from a Norwegian hospital’s working-time register encompassed information on quick returns (<11 hours between shifts), day-, evening-, night-, and long (≥12 hours) shifts worked during 2020, and were linked to questionnaire data from 1195 healthcare workers collected in January 2021. The questionnaire assessed work-related accidents causing harm to oneself, patients/others, and/or equipment the last year, as well as dozing off at work the last month and/or during commute the last year. Data were analyzed using negative binomial regressions, adjusting for age, sex, children, marital status, shift work experience, monthly working hours, circadian type, and night shifts. RESULTS: Number of quick returns the last year was positively associated with causing harm to oneself [incidence rate ratio (IRR) 1.021, 95% confidence interval (CI) 1.009–1.034]. Number of day shifts and evening shifts were negatively associated with causing harm to patients/others (IRR 0.987, 95% CI 0.981–0.992; IRR 0.989, 95% CI 0.982–0.996, respectively). Number of night shifts was positively associated with dozing off at work (IRR 1.005, 95% CI 1.002–1.008) and during commute (IRR 1.007, 95% CI 1.003–1.010), but was not associated with work-related accidents. Number of long shifts was positively associated with healthcare workers causing harm to oneself (IRR 1.198, 95% CI 1.111–1.291), patients/others (IRR 1.209, 95% CI 1.122–1.304), and equipment (IRR 1.174, 95% CI 1.080–1.275). CONCLUSION: Limiting quick returns and long shifts may be relevant considerations for improving employee and patient safety.

Shift work (SW) encompasses 20% of the European workforce. Moreover, high blood pressure (BP) remains a leading cause of death globally. This review aimed to synthesize the magnitude of the potential impact of SW on systolic blood pressure (SBP), diastolic blood pressure (DBP) and hypertension (HTN). MEDLINE, EMBASE and CENTRAL databases were searched for epidemiological studies evaluating BP and/or HTN diagnosis among shift workers, compared with day workers. Random-effects meta-analyses were performed and the results were expressed as pooled mean differences or odds ratios and 95% confidence intervals (95% CI). The Newcastle–Ottawa Scale was used to assess the risk of bias. Forty-five studies were included, involving 117,252 workers. We found a significant increase in both SBD and DBP among permanent night workers (2.52 mmHg, 95% CI 0.75–4.29 and 1.76 mmHg, 95% CI 0.41–3.12, respectively). For rotational shift workers, both with and without night work, we found a significant increase but only for SBP (0.65 mmHg, 95% CI 0.07–1.22 and 1.28 mmHg, 95% CI 0.18–2.39, respectively). No differences were found for HTN. Our findings suggest that SW is associated with an increase of BP, mainly for permanent night workers and for SBP. This is of special interest given the large number of susceptible workers exposed over time.

Free-space optical (FSO) communication system provides several advantages over radio frequency (RF) system offering high bandwidth, low cost, small space requirements and more secure transmission which is free from Electromagnetic Interference (EMI). However, when the transmitted light signal passes through the atmosphere it experiences attenuation and fluctuations due to atmospheric turbulence. This paper analyzes the bit error rate (BER) performance of FSO communication systems under strong atmospheric turbulence for on-off keying (OOK), binary phase-shift keying (BPSK), differential phase shift keying (DPSK), quadrature phase shift keying (QPSK) and 8-phase shift keying (8-PSK) for link distances of 500, 1,000, 1,500 and 2,000 m. The probability density function (pdf) of the received irradiance is modelled using the gamma-gamma distribution model. It is found that the system exhibits the best BER performance and compensates the lowest power penalty at BER of 10 for BPSK modulation compared with other modulation techniques which makes BPSK more appropriate to be used with FSO turbulent system.

Background: Shift‐work schedules can cause sleep and psychological problems among nurses, negatively affecting their health and quality of life. This trial examined the effects of low‐energy light therapy on sleep, psychological symptoms, and heart rate variability among shift‐work nurses. Methods: This randomized controlled trial was conducted from July 2021 to June 2022. The inclusion criteria were nurses with self‐reported insomnia who worked in shifts in the last 6 months in a medical center in northern Taiwan. Block randomization was used to assign the study participants to two groups: experimental ( n = 32) and control ( n = 32). A portable Meridian Aura Cap equipped with a low‐level light‐emitting diode was used to provide red and near‐infrared light (660 and 850 nm) for 30 min, three times a week for 4 weeks; the control group did not receive any intervention. The Depression Anxiety Stress Scale‐21 and Insomnia Severity Index were used to measure psychological symptoms and sleep problems, respectively. Heart rate variability was measured by the ANSWatch. Results: No significant differences were reported in preintervention scores. After the 4‐week intervention, the intervention group scored significantly lower in insomnia (4.3 vs. 12.6, respectively; p < 0.001), depression (2.5 vs. 7.9, p < 0.001), anxiety (3.1 vs. 9.2, p < 0.001), and stress (5.6 vs. 12, p < 0.001) than those in the controls. No significant differences were observed in heart rate variability between the two groups. Conclusion: Low‐level light‐emitting diode light therapy improved sleep quality in shift‐work nurses with insomnia and alleviated depression, anxiety, and stress symptoms; however, it did not improve heart rate variability, possibly because of the short intervention duration and the ongoing shift‐work schedule. Implications for Nursing Management: Employers could consider providing phototherapy for shift nurses to improve their health. Trial Registration: ClinicalTrials.gov identifier: NCT05146596

Abstract 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 caffeine intake of US adults working various shifts were assessed. Methods The 24-hour dietary recall data from NHANES 2005–2010 (N = 8,500) were used to estimate caffeine intake from foods and beverages. Work shifts were self-reported as follows: regular day shift; evening shift; night shift; rotating shift; or other shift. Regression analyses assessed associations of shift work with caffeine intake after adjustment for sociodemographic factors. Results Approximately 74% of employed adults were day-shift workers and 26% were nonday-shift workers. Night-shift workers slept for 6.25 ± 0.09 hours per day, somewhat less than day-shift workers who only slept 6.83 ± 0.02 hours (p < .0001). Mean 24-hour weekday caffeine intake of evening-, night-, and rotating-shift workers (217 ± 23, 184 ± 19, and 206 ± 15 mg, respectively) was similar (p > .3) to day-shift workers (203 ± 5 mg). Regardless of work schedule, individuals consumed the most caffeine during morning hours. Evening- and night-shift workers reported consuming 36%–46% less caffeine during their work hours and 72%–169% more during nonwork hours than day-shift workers (p < .01). Conclusions Total daily caffeine intake of shift workers is similar to nonshift workers; most caffeine is consumed in the morning regardless of shift. Because shift workers consume less caffeine during regular work hours and more during nonwork hours than day workers, they may be using caffeine to, in part, optimize off-duty alertness.