Sleep habits, alertness, cortisol levels, and cardiac autonomic activity in short-distance bus drivers: differences between morning and afternoon shifts

An Exploratory Study of Sleep-Wake Differences of Autonomic Activity in Patients with Mild Cognitive Impairment: The Role of Melatonin as a Modulating Factor

Purpose

The objective of the present study was to assess sleep-wake differences of autonomic activity in patients with mild cognitive impairment (MCI) compared to control subjects. As a post-hoc objective, we sought to evaluate the mediating effect of melatonin on this association.

Patients and Methods

A total of 22 MCI patients (13 under melatonin treatment) and 12 control subjects were included in this study. Sleep-wake periods were identified by actigraphy and 24hr-heart rate variability measures were obtained to study sleep-wake autonomic activity.

Results

MCI patients did not show any significant differences in sleep-wake autonomic activity when compared to control subjects. Post-hoc analyses revealed that MCI patients not taking melatonin displayed lower parasympathetic sleep-wake amplitude than controls not taking melatonin (RMSSD -7 ± 1 vs 4 ± 4, p = 0.004). In addition, we observed that melatonin treatment was associated with greater parasympathetic activity during sleep (VLF 15.5 ± 0.1 vs 15.1 ± 0.1, p = 0.010) and in sleep-wake differences in MCI patients (VLF 0.5 ± 0.1 vs 0.2 ± 0.0, p = 0.004).

Conclusion

These preliminary findings hint at a possible sleep-related parasympathetic vulnerability in patients at prodromal stages of dementia as well as a potential protective effect of exogenous melatonin in this population.

Stressed at Work: Investigating the Relationship between Occupational Stress and Salivary Cortisol Fluctuations

Chronic stress has been associated with a range of health disparities, but examination of occupational stress, especially in the wake of COVID-19, has been minimal for many careers. A novel methodology involving work stress diaries and collection of salivary cortisol was employed to determine correlations between occupations, occupational stressors, and how well these are related to the physiological response to stress exposure, the release of cortisol. While cortisol levels tended to follow typical circadian rhythm based on sampling times, cortisol levels also followed the subjective stress levels listed in the work stress diaries following linear regression analysis using the pooled study population data (p = 0.042). When comparing the stressors between the studied careers, participants who worked in the healthcare industry accounted for one-third of the total participants, but reported nearly half (42%) of the more severe occupational stressors listed in the diaries. Finally, the most commonly listed emotional reactions to exposures listed included feelings of stress, frustration, anger, anxiety, or overwhelm. As the workplace progresses from the pandemic, the opportunity to reduce occupational stress exposures in the workplace is at hand. Companies that work towards minimizing the stress faced by their workforce would have a healthier and more relaxed workforce.

Expression profile of circular RNAs in continuous light-induced ovarian dysfunction

PURPOSE

This study aims to elucidate the underlying relationship between the expression profiles of circular RNAs (circRNAs) and the ovarian dysfunction induced by continuous light.

METHODS

High-throughput sequencing was used to profile the transcriptome of differentially expressed circRNAs (DEcircRNAs) in rat ovary under continuous light exposure (12 h:12 h light/light cycle, L/L group) and a control cycle (12 h:12 h light/dark cycle, L/D group). Gene ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and circRNAs-microRNAs-messenger RNAs networks were performed to predict the role of DEcircRNAs in biological processes and pathways. A quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) assay was conducted to verify the high-throughput sequencing results and the expression level of circadian rhythm genes.

RESULTS

In total, 305 circRNAs were differentially expressed between the L/L and L/D groups. Among these, 211 circRNAs were up regulated, while 94 were down regulated. Eight candidate circRNAs from 305 DEcircRNAs were verified by qRT-PCR. Further bioinformatics analysis revealed that interactions between DEcircRNAs and a set of microRNAs involved in ovarian dysfunction-related pathways, such as regulation of androgen receptors, gonadotrophin releasing hormone signaling pathway, endocrine resistance, etc. Subsequently, we identified rno_circ:chr2:86868285-86964272 and rno_circ:chr1:62330221-62360073 may participate in the pathophysiology of ovarian dysfunction by constructing circRNAs-microRNAs-messenger RNAs networks. Meanwhile, constant light reduced the expression of circadian rhythm genes CLOCK, BAML1, PER1, and PER2 compared with that of controls. Caspase3 and Bax were up regulated in the L/L group compared with the L/D group, while Bcl-2 was down regulated.

CONCLUSIONS

In summary, the results reveal that the expression profiles and potential functions of DEcircRNAs in rat ovaries may play important roles in continuous light-induced ovarian dysfunction. These findings provide novel clues and molecular targets for studying the mechanisms and clinical therapy of ovarian dysfunction.

Exploring the Effects of Energy Constraints on Performance, Body Composition, Endocrinological/Hematological Biomarkers, and Immune System among Athletes: An Overview of the Fasting State

The Ramadan fasting period (RFP) means abstaining from consuming food and/or beverages during certain hours of the day—from sunrise to sunset. Engaging in exercise and sports during the RFP leads to the lipolysis of adipose tissue and an increase in the breakdown of peripheral fat, leading to an increase in fat consumption. The effects of the RFP on functional, hematological, and metabolic parameters needs further study as existing studies have reported contradictory results. The differences in the results of various studies are due to the geographical characteristics of Muslim athletes, their specific diets, and their genetics, which explain these variations. In recent years, the attention of medical and sports researchers on the effects of the RFP and energy restrictions on bodily functions and athletic performance has increased significantly. Therefore, this brief article examines the effects of the RFP on the immune system, body composition, hematology, and the functionality of athletes during and after the RFP. We found that most sporting activities were performed during any time of the day without being affected by Ramadan fasting. Athletes were able to participate in their physical activities during fasting periods and saw few effects on their performance. Sleep and nutritional factors should be adjusted so that athletic performance is not impaired.

Effects of safety pattern, cabin ergonomics, and sleep on work-related stress and burnout of city and transit bus drivers in Lahore, Pakistan

The health and working environment of bus drivers is compromised in low-middle-income countries like Pakistan which leads to burnout and excessive Road Traffic Crashes. Hence, this study delves into factors affecting their safe operations from health and work environment perspectives and measures their associated stress and Burnout level. In a study of four hundred and ninety-nine (499), 86% city and 14% transit bus drivers are surveyed through a questionnaire. Stress is estimated for city and transit bus drivers, using the Effort/Reward Imbalance Model (ERI) of Siegrist, and burnout is calculated using the Copenhagen Burnout Inventory (CBI). For the determination of important determinants, descriptive and regression analyses are conducted. Findings show that stress has emerged as a negative factor for the physical and psychological health of city and transit bus drivers. Results based on bus drivers' responses suggest that organisational awareness and emphasis on health and safety levels can significantly reduce driver stress and burnout. Practitioner Summary: This study explores burnout and work-related stress of bus drivers in Lahore (Pakistan). City and transit bus drivers were interviewed through a questionnaire, containing three sections, using different subjective ratings based upon their past reliability. Results indicate that stress in bus drivers emerged as a physical and psychological health-damaging factor.

cardiac autonomic control and neural arousal as indexes of fatigue in professional bus drivers

Background

Bus driving is a mentally demanding activity that requires prolonged attention to ensure safety. The aim of the study was to assess mental fatigue caused by driving a public bus and to find a profile of workers at higher risk.

Methods

We evaluated changes of critical flicker fusion (CFF) (index of central arousal) and heart rate variability (HRV) (index of autonomic balance) in a 6-hour driving shift on a real route, in 31 professional bus drivers, and we tested the influence of personal factors such as sleep quality, BMI, and age. Paired t-test was used to test differences of CFF and HRV between both initial and final phase of driving, while multiple linear regression tested the influence of personal variables on the indexes of mental fatigue.

Results

Results showed that CFF significantly decreased after 6 hours of bus driving (41.91 Hz, sd 3.31 vs. 41.15 Hz, sd 3.15; p = 0.041), and heart rate significantly decreased in the final phase of driving, with respect to the initial phase (85 vs. 78 bpm, p = 0.027). Increasing age (beta = -0.729, p = 0.022), risk of obstructive sleep apnea syndrome (beta = -0.530, p = 0.04), and diurnal sleepiness (beta = -0.406, p = 0.017) showed a significant effect on influencing mental fatigue.

Conclusion

Elderly drivers at higher risk of sleep disorders are more prone to mental fatigue, when exposed to driving activity. Monitoring indexes of central arousal and autonomic balance, coupled with the use of structured questionnaires can represent a useful strategy to detect profile of workers at higher risk of mental fatigue in such duty.

Diurnal Cortisol Rhythm in Female Flight Attendants

The work of flight attendants is associated with exposure to long-term stress, which may cause increased secretion of cortisol. The aim of the study is to determine the circadian rhythm of cortisol and to seek factors of potential influence on the secretion of cortisol in female flight attendants working within one time zone as well as on long-distance flights. The prospective study covers 103 women aged 23-46. The study group (I) was divided into two subgroups: group Ia, comprising female flight attendants flying within one flight zone, and group Ib, comprising female flight attendants working on long-distance flights. The control group (II) are women of reproductive age who sought medical assistance due to marital infertility in whom the male factor was found to be responsible for problems with conception in the course of the diagnostic process. The assessment included: age, BMI, menstrual cycle regularity, the length of service, the frequency of flying, diurnal profile of the secretion of cortisol, testosterone, estradiol, 17-OH progesterone, SHBG, androstenedione, and progesterone concentration. Descriptive methods and inferential statistics methods were used to compile the data. Comparing the profile of flight attendants from groups Ia and Ib shows that the curve flattened among women flying within one time zone. The secretion curve is also more flattened in women with less years worked and in flight attendants working less than 60 h per month. Due to the character of work, the female flights attendants do not have hypersecretion of cortisol. Frequency of flying and length of work affect the dysregulation of HPA axis.

Risk Factors for Collisions and Near-Miss Incidents Caused by Drowsy Bus Drivers

Serious accidents have been caused by drowsy bus drivers and have necessitated an examination of the risk factors involved. A questionnaire survey among employees of a bus company was conducted in Ibaraki Prefecture, Japan in September 2014. Respondents were asked to report details of their work and life over the preceding month. The 301 valid responses by bus drivers (295 men and 6 women) with a mean age of 51.6 years (range: 24–73 years) were used for analysis. Univariable logistic regression showed that factors affecting the incidence of collisions and near-miss incidents by drowsy drivers were continued driving when feeling sick, reporting a physical condition, number of sleep hours, time spent with family, working hours, and nutritional balance. According to a multiple regression analysis, continued driving when feeling sick (odds ratio: 3.421, 95% confidence interval: 1.618–7.231) was the only significant risk for the event. Managers should encourage drivers to voluntarily report poor health and should provide opportunities to stop driving if drivers experience physical discomfort or sleepiness. To improve road safety, educational measures are required for both drivers and managers to prevent driving under poor health conditions, although the decision to stop driving depends on drivers’ subjective judgment.

Sleep misalignment and circadian rhythm impairment in long-haul bus drivers under a two-up operations system

OBJECTIVES

The objective of the study was to describe working and sleep conditions and to assess how sleep opportunities are associated with obtained sleep and alertness, in a sample of long-haul bus drivers working with a two-up operations system.

METHODS

Measures of subjective sleep and sleepiness, actigraphy, circadian temperature rhythm, and psychomotor vigilance tasks were obtained from a sample of 122 drivers from Argentina. Variables were compared between high and low fatigue risk groups, which were formed using a median split of a fatigue risk score. The score was calculated based on drivers' total working hours, maximum shift duration, minimum short break duration, maximum night work per seven days, and long break frequencies.

RESULTS

Considering a standardized one-day period, sleep in the bus accounted for 1.9±0.1 h of total sleep (57±1% efficiency), sleep at destination for 1.6±0.2 h of total sleep (90±1% efficiency), and sleep at home for 3.8±0.2 h of total sleep (89±1% nap efficiency and 90±1% anchor sleep efficiency). In drivers exposed to high-risk working schedules, the circadian temperature rhythm was weaker (lower % of variance explained by the model) (22.0±1.7% vs. 27.6±2.0%, p <0.05) and without a significant acrophase.

CONCLUSIONS

Drivers obtained a total amount of weekly sleep similar to the recommended levels for adults, but distributed at different locations and at different times during the day. High-risk working schedules were associated with disruption of circadian temperature rhythms. These results point out to the need of the implementation of shift-work scheduling strategies to minimize sleep misalignment and circadian desynchronization in long-haul bus drivers.

Factors associated with sleep quality of Thai intercity bus drivers

This study aimed to describe sleep quality and explore factors associated with poor sleep quality in Thai intercity bus drivers. A cross-sectional design was employed with a sample of intercity bus drivers from 4 bus transportation companies. The Thai-PSQI was used to identify sleep quality, and the Thai Berlin Questionnaire used to assess sleep apnea risk. Data analysis included descriptive statistics and logistic regression. A total of 338 surveys were analyzed. All bus drivers were male; almost 66% of the bus drivers were defined as poor sleepers, and 18.1% were assessed as being at high risk for obstructive sleep apnea. Working night shifts (OR=20.6), rotating day or night shifts (OR=17.0), alcohol consumption (OR=2.7), being married (OR=3.1), and not exercising (OR=2.3) were related to poor sleep quality. The majority of the Thai intercity bus drivers in our study reported poor sleep quality indicating that action is required at both company and individual levels to encourage the adoption of healthy lifestyles and improvement of working conditions.

The Concept of Qailulah (Midday Napping) from Neuroscientific and Islamic Perspectives

Napping/siesta during the day is a phenomenon, which is widely practised in the world. However, the timing, frequency, and duration may vary. The basis of napping is also diverse, but it is mainly done for improvement in alertness and general well-being. Neuroscience reveals that midday napping improves memory, enhances alertness, boosts wakefulness and performance, and recovers certain qualities of lost night sleep. Interestingly, Islam, the religion of the Muslims, advocates midday napping primarily because it was a practice preferred by Prophet Muhammad (pbuh). The objectives of this review were to investigate and compare identical key points on focused topic from both neuroscientific and Islamic perspectives and make recommendations for future researches.

Relationship between Cognitive and Sleep-wake Variables in Asymptomatic Offspring of Patients with Late-onset Alzheimer's Disease

Early neuropathological changes characteristic of late-onset Alzheimer's disease (LOAD) involve brain stem and limbic structures that regulate neurovegetative functions, including sleep-wake rhythm. Indeed, sleep pattern is an emerging biomarker and a potential pathophysiological mechanism in LOAD. We hypothesized that cognitively asymptomatic, middle-aged offspring of patients with LOAD (O-LOAD) would display a series of circadian rhythm abnormalities prior to the onset of objective cognitive alterations. We tested 31 children of patients with LOAD (O-LOAD) and 19 healthy individuals without family history of Alzheimer's disease (control subjects, CS) with basic tests of cognitive function, as well as actigraphy measures of sleep-wake rhythm, cardiac autonomic function, and bodily temperature. Unexpectedly, O-LOAD displayed subtle but significant deficits in verbal episodic memory (Rey Auditory Verbal Learning Test delayed recall 10.6 ± 0.4 vs. 8.6 ± 0.6, t = 4.97, df = 49, p < 0.01) and language (Weschler's vocabulary 51.4 ± 1.3 vs. 44.3 ± 1.5, t = 2.49, df = 49, p < 0.001) compared to CS, even though all participants had results within the clinically normal range. O-LOAD showed a phase-delayed rhythm of body temperature (2.56 ± 0.47 h vs. 3.8 ± 0.26 h, t = 2.48, df = 40, p = 0.031). Cognitive performance in O-LOAD was associated with a series of cardiac autonomic sleep-wake variables; specifically indicators of greater sympathetic activity at night were related to poorer cognition. The present results suggest sleep pattern deserves further study as a potential neurobiological signature in LOAD, even in middle-aged, at risk individuals.

Shift work and endocrine disorders

The objective of this review was to investigate the impact of shift and night work on metabolic processes and the role of alterations in the sleep-wake cycle and feeding times and environmental changes in the occurrence of metabolic disorders. The literature review was performed by searching three electronic databases for relevant studies published in the last 10 years. The methodological quality of each study was assessed, and best-evidence synthesis was applied to draw conclusions. The literature has shown changes in concentrations of melatonin, cortisol, ghrelin, and leptin among shift workers. Melatonin has been implicated for its role in the synthesis and action of insulin. The action of this hormone also regulates the expression of transporter glucose type 4 or triggers phosphorylation of the insulin receptor. Therefore, a reduction in melatonin can be associated with an increase in insulin resistance and a propensity for the development of diabetes. Moreover, shift work can negatively affect sleep and contribute to sedentarism, unhealthy eating habits, and stress. Recent studies on metabolic processes have increasingly revealed their complexity. Physiological changes induced in workers who invert their activity-rest cycle to fulfill work hours include disruptions in metabolic processes.

Sleep habits, daytime sleepiness and working conditions in short-distance bus drivers

Purpose

– Driving needs high levels of alertness. Increased somnolence is the most important negative influence to maintain proper watchfulness and vigilance. Drowsiness, working conditions and their affective impact must be taken into account to determine driving safety. The purpose of this paper is to assess excessive daytime sleepiness, sleep habits, quality of sleep, stress-related symptoms, and working conditions in a large sample of short-distance bus drivers in the city of Buenos Aires.

Design/methodology/approach

– This was a cross-sectional study performed to evaluate sleep habits and obstructive apnea risk in short-distance bus drivers of the Metropolitan Area of Buenos Aires, Argentina. Questionnaires regarding anthropometric data, sleep habits, snoring, daytime sleepiness (Epworth Sleepiness Scale), quality of sleep (Pittsburgh Quality of Sleep Index, PQSI), working conditions and fatigue and anxiety related to work were administered to professional short-distance bus drivers (n=1023).

Findings

– A prevalence of 34.6 percent of obesity and 80 percent of snoring was observed. Mean sleep time during workdays was 6.5±0.1 h and bad sleep quality was reported by 54.6 percent of the subjects. Excessive daytime sleepiness had a prevalence of 48.8 percent and was independently associated with reduced sleep time, increased sleep debt, long time to wake up, snoring, and short resting time along the working day (p<0.05).

Originality/value

– Short-distance drivers in Buenos Aires, the largest urban area of Argentina, are a partially sleep-deprived, overweighted population, showing a high daytime somnolence, poor work-rest conditions and high levels of anxiety and fatigue. This association can be very harmful in view of the demanding working conditions considered.

Circadian Activity Rhythms and Sleep in Nurses Working Fixed 8-hr Shifts

Shift work is associated with adverse health outcomes. The aim of this study was to explore the effects of shift work on circadian activity rhythms (CARs) and objective and subjective sleep quality in nurses. Female day-shift (n = 16), evening-shift (n = 6), and night-shift (n = 13) nurses wore a wrist actigraph to monitor the activity. We used cosinor analysis and time-frequency analysis to study CARs. Night-shift nurses exhibited the lowest values of circadian rhythm amplitude, acrophase, autocorrelation, and mean of the circadian relative power (CRP), whereas evening-shift workers exhibited the greatest standard deviation of the CRP among the three shift groups. That is, night-shift nurses had less robust CARs and evening-shift nurses had greater variations in CARs compared with nurses who worked other shifts. Our results highlight the importance of assessing CARs to prevent the adverse effects of shift work on nurses' health.

Influences of early shift work on the diurnal cortisol rhythm, mood and sleep: within-subject variation in male airline pilots

We aimed to investigate how early and late work shifts influenced the diurnal cortisol rhythm using a within-subjects study design. Participants were 30 healthy male non-smoking pilots, mean age 39.4, employed by a short-haul airline. The standard rotating shift pattern consisted of 5 early shifts (starting before 0600 h), followed by 3 rest days, 5 late shifts (starting after 1200 h) and 4 rest days. Pilots sampled saliva and completed subjective mood ratings in a logbook 6 times over the day on two consecutive early shift days, two late days and two rest days. Sampling was scheduled at waking, waking+30 m, waking+2.5 h, waking+8 h, waking+12 h and bedtime. Waking time, sleep duration, sleep quality and working hours were also recorded. Cortisol responses were analysed with repeated measures analysis of variance with shift condition (early, late, rest) and sample time (1-6) as within-subject factors. Early shifts were associated with a higher cortisol increase in response to awakening (CAR(i)), a greater total cortisol output over the day (AUC(G)) and a slower rate of decline over the day than late shifts or rest days. Early shifts were also associated with shorter sleep duration but co-varying for sleep duration did not alter the effects of shift on the cortisol rhythm. Both types of work shift were associated with more stress, tiredness and lower happiness than rest days, but statistical adjustment for mood ratings did not alter the findings. Early shift days were associated with significantly higher levels of circulating cortisol during waking hours than late shifts or rest days.

Excessive sleepiness prevalence in public transportation drivers of a developing country

OBJECTIVE

To determine the prevalence of excessive sleepiness (ES) in bus and auto-rickshaw drivers from Lima, Peru.

METHODS

We conducted a cross-sectional study of Lima's bus and auto-rickshaw drivers to estimate ES prevalence in this population. Survey sites were private transportation companies, systematically selected with a snowball approach. ES was assessed with the Spanish-validated version of the Epworth sleep questionnaire (ESQ) with a cutoff score >10. We obtained relevant demographic information.

RESULTS

Four hundred and thirty-four bus and auto-rickshaw drivers were eligible for analysis. The overall ES prevalence was 32.7 percent (95% confidence interval [CI]: 28-37.2). ES prevalence was higher in bus drivers than in auto-rickshaw drivers, 38 percent (95% CI: 31.7-44.2) and 26.9 percent (95% CI: 20.6-33.1), respectively (P = .01). We used data from all subjects to obtain regression equations for ESQ score with several predictors. Being a bus driver, working additional nighttime hours per week, having depression or anxiety, and alcohol abuse had small but significant associations with ESQ scores.

CONCLUSION

ES prevalence in Lima's public transportation drivers is in a medium range as suggested by previous regional studies.

Stress, workload and physiology demand during extravehicular activity: a pilot study

Background:

Extravehicular activity (EVA), such as exercise performed under unique environmental conditions, is essential for supporting daily living in weightlessness and for further space exploration like long Mars mission.

Aim:

The study was planned stress, workload, and physiological demands of simulated Mars exploration.

Materials and Methods:

In this study, the six-person crew lived (24 hours) for 14 days during a short-term stay at the Mars Desert Research Station. The heart rates, salivary cortisol, workload, peak oxygen uptake or maximal aerobic capacity of the crew are measured before, during and after an EVA.

Results:

Data for heart rate showed the same trend as peak oxygen uptake or maximal aerobic capacity, with a maximal increase to 85% of peak. The rating of subscale showed a significant increase in EVA as compared to run. Salivary cortisol levels and heart rates were increased in both groups, although significant increased of cortisol levels and heart rates more in EVA as compared to hill running crew members.

Conclusion:

Further study is required on large scale taken into account of limitations of this study and including other physiological and psychological parameters in Mars analog environment.

Morning cortisol levels and perceived stress in irregular shift workers compared with regular daytime workers

The 24/7 work environment and irregular shifts may markedly enhance the psychological pressure of media work. Changes in the hypothalamic-pituitary-adrenal axis reflect adaptation to stress. We analysed the correlation between subjective stress, sleep, salivary cortisol, and melatonin hormones among Finnish media workers with regular daytime work (RDW) and with irregular shift work (ISW) while controlling confounders. From 874 employees with regular daytime work or with irregular shift work, 70 employees from both groups were randomly selected. The final number of employees with a complete salivary cortisol profile was 66 in the RDW group and 65 in the ISW group. Five saliva samples were gathered from each subject before and during a working day. The salivary cortisol level of the sample taken 60 minutes after awakening (T1) was compared to the salivary cortisol level taken immediately after awakening (T0, T1/T0 ratio). The ratio was higher in the ISW group than in RDW group. Irregular shift work (P < 0.001), severe stress (P < 0.05), and less sleep (P < 0.05) were independently associated with an augmented cortisol response after awakening. A stressful work environment and irregular shift work enhance cortisol excretion after waking. In the long run, this may become detrimental to health.