Early morning awakening and nonrestorative sleep are associated with increased minor non-fatal accidents during work and leisure time

Nonrestorative sleep and its associated factors in Chinese adolescents and the moderation effects of coffee or tea consumption

BACKGROUND

Nonrestorative sleep (NRS) is related to numerous adverse outcomes. There is rare evidence of its associated factors, especially in Chinese adolescents. This study aimed to explore the factors associated with NRS in Chinese adolescents and the potential moderation effects of coffee or tea consumption.

METHODS

This cross-sectional study invited adolescents attending Grades 7-11 in Nanjing, China, to complete a self-administered questionnaire, including their NRS, stress, anxiety, physical symptoms, depression, sociodemographics, and lifestyles. Linear regressions were applied to investigate the associated factors of their NRS, with the moderation effects of coffee or tea consumption and other characteristics being tested by additionally including their interactions.

RESULTS

Totally 481 adolescents (49% male, age 15.5 ± 1.5 years) were enrolled, with the average global NRS score of 42.16 ± 7.57. Higher family income (β = 2.01, P = 0.007), longer sleep duration (β = 2.33, P = 0.011), and moderate after-class activity (β = 1.50, P = 0.044) contributed less NRS, while higher educational level (β = -2.60, P = 0.033), more coffee or tea consumption (β = -1.68, P = 0.013), physical symptoms (β = -3.85, P < 0.001), stress (β = -0.23, P = 0.005), anxiety (β = -1.54, P = 0.045), and depression (β = -0.13, P = 0.014) contributed more NRS. Females (β = 0.82, P = 0.005), older age (β = -0.46, P = 0.029), and higher education level (β = -1.68, P < 0.001) contributed less refreshment from sleep, more physical/medical symptoms of NRS, and less daytime function, respectively. Coffee or tea consumption moderated the associations of somatic symptoms (β = 0.25, P = 0.021), stress (β = 0.29, P = 0.022), anxiety (β = 0.27, P = 0.005), and depression (β = 0.17, P = 0.021) with NRS.

CONCLUSIONS

Longer sleep duration, moderate after-class activity, reduced coffee or tea consumption, and promotion of physical and mental health may help reduce adolescents' NRS. Coffee or tea consumption may help buffer the negative associations of somatic symptoms, stress, anxiety, and depression with NRS.

Elevating understanding: Linking high-altitude hypoxia to brain aging through EEG functional connectivity and spectral analyses

High-altitude hypoxia triggers brain function changes reminiscent of those in healthy aging and Alzheimer's disease, compromising cognition and executive functions. Our study sought to validate high-altitude hypoxia as a model for assessing brain activity disruptions akin to aging. We collected EEG data from 16 healthy volunteers during acute high-altitude hypoxia (at 4,000 masl) and at sea level, focusing on relative changes in power and aperiodic slope of the EEG spectrum due to hypoxia. Additionally, we examined functional connectivity using wPLI, and functional segregation and integration using graph theory tools. High altitude led to slower brain oscillations, that is, increased δ and reduced α power, and flattened the 1/f aperiodic slope, indicating higher electrophysiological noise, akin to healthy aging. Notably, functional integration strengthened in the θ band, exhibiting unique topographical patterns at the subnetwork level, including increased frontocentral and reduced occipitoparietal integration. Moreover, we discovered significant correlations between subjects' age, 1/f slope, θ band integration, and observed robust effects of hypoxia after adjusting for age. Our findings shed light on how reduced oxygen levels at high altitudes influence brain activity patterns resembling those in neurodegenerative disorders and aging, making high-altitude hypoxia a promising model for comprehending the brain in health and disease.

The effect of job satisfaction regulating workload on miners' unsafe state

Miners’ unsafe behavior is the main cause of accidents in coal mines, and unsafe state have an important influence on unsafe behavior among miners. To minimize accidents from the source of accident chain, we evaluated the impact of workload on miners’ unsafe state. It is important for coal enterprises to monitor miners’ unsafe state and to prevent unsafe accidents. Workload is divided into two dimensions: work time and work demand. Meanwhile, we introduced job satisfaction as a moderating variable. Through empirical research methods, first-line employees from two coal mines in China were enrolled in the questionnaire survey. Regression analysis was used to verify the impact of workload and its various dimensions, job satisfaction, and miners’ unsafe state. We found that workload, work time and work demand have significant positive effects on miners’ unsafe state. Job satisfaction plays a moderating effect in the relationship between workload and miners’ unsafe state. To some extent, a higher job satisfaction was associated with reduced workload, reduced occurrence of miners’ unsafe state and minimal incidences of unsafe accidents. On this basis, measures were proposed to improve miners’ unsafe state in terms of workload and job satisfaction. This study informs the establishment of effective intervention measures to monitor miners’ unsafe state and is also beneficial to the improvement of coal mine safety.

Measurement properties of the simplified Chinese version of Nonrestorative Sleep Scale in adolescents

This study aimed to assess the measurement properties of a simplified Chinese version of the Nonrestorative Sleep Scale (NRSS) among adolescents. We obtained a simplified Chinese NRSS by the standard forward-backward translation procedures and administered it to 486 students who were attending Grade 7-11 in Nanjing, China. Furthermore, Pittsburgh Sleep Quality Index, Athens Insomnia Scale, Centre for Epidemiological Studies Depression Scale, and Toronto Hospital Alertness Test were also self-completed for measuring sleep quality, insomnia, depression and alertness respectively. The sample was randomly split into two halves, with the first half used to explore the scale structure by exploratory factor analysis (EFA), and the second half used to confirm the identified structure by confirmatory factor analysis (CFA). A total of 481 adolescents (49% male) with a mean age of 16 years (range: 13-18) completed this study. In the other half of 250 adolescents, the root mean square error of approximation (RMSEA), standardised root mean square residual, and comparative fit index (CFI) in CFA, which tested the four-factor structure obtained from EFA, were 0.062, 0.051 and 0.975, respectively. Convergent validity was demonstrated from a significant correlation of the simplified Chinese NRSS with sleep quality (r = -0.62), insomnia (r = -0.71), depression (r = -0.60) and alertness (r = 0.54). The internal consistency and test-retest reliability for the global scale were 0.83 and 0.86 respectively. Measurement invariance was established between males and females with the changes of both CFI and RMSEA < 0.01. The simplified Chinese NRSS is valid and reliable for measuring NRS among Chinese adolescents.

Sleep duration and sleep difficulties as predictors of occupational injuries: a cohort study

STUDY OBJECTIVES

To examine the association between sleep duration and sleep difficulties with different types and causes of workplace and commuting injuries.

METHODS

The data were derived from the Finnish Public Sector study including 89.543 participants (178.309 person-observations). Participants reported their sleep duration and sleep difficulties between 2000 and 2012. These were linked to occupational injury records from the national register maintained by the Federation of Accident Insurance Institutions. Risk of injuries was followed up 1 year after each study wave. Logistic regression analysis with generalised estimating equations (GEEs) was used to examine the association between sleep duration/difficulties and risk of injuries, and multinomial logistic regression with GEE was used to examine the association with injury types and causes.

RESULTS

Both sleep duration and difficulties were associated with injuries. Employees with short sleep (≤6.5 hours) had 1.07-fold odds of workplace injuries (95% CI 1.00 to 1.14) and 1.14 times higher odds of commuting injuries (95% CI 1.04 to 1.26) compared with employees with normal sleep duration. For employees with disturbed sleep, the corresponding ORs were 1.09-fold (95% CI 1.02 to 1.17) and 1.14-fold (95% CI 1.04 to 1.26) compared with those without sleep difficulties, respectively. The risk of commuting injuries was higher among those who had difficulty in falling asleep (OR 1.29, 95% CI 1.07 to 1.55), woke up too early (OR 1.11, 95% CI 1.00 to 1.23) or had non-restorative sleep (OR 1.18, 95% CI 1.05 to 1.33).

CONCLUSIONS

Short sleep duration and sleep difficulties are associated with slightly increased risk of workplace and commuting injuries.

Association between Non-Restorative Sleep and Quality of Life in Chinese Adolescents

To examine non-restorative sleep and its impact on quality of life (QOL) in Chinese adolescents, this cross-sectional study included 2827 students aged 12–20 who were selected from 15 secondary schools in Hong Kong, China. Non-restorative sleep was assessed by a single item, rated on a 0–10 scale: “To what extent did you feel refreshed upon awakening over the past month?”. QOL was evaluated by the World Health Organization Quality of Life Measure—Abbreviated Version Hong Kong Chinese Version. Univariable and multivariable linear mixed-effects regressions were conducted to examine the influence of non-restorative sleep (NRS) on QOL. In the present sample, the mean overall QOL was 13.83, and the extent of feeling refreshed upon awakening was 4.75 on average. In multivariable linear mixed-effects regression, one unit feeling less refreshed upon awakening was associated with 0.37 units of poorer overall QOL after adjusting for age, gender, medical conditions, parental education and occupation, weekly hours of aerobic exercises, smoking and drinking habits. Additionally, adolescents with a significantly poorer overall QOL were more likely to be older, have medical problems, have parents with an educational level of primary school or below, have an unemployed father, engage in less weekly aerobic exercise, and be current smokers or former drinkers. Adolescents who experienced non-restorative sleep had a poorer QOL. Future studies are needed to alleviate non-restorative sleep to improve health outcomes in adolescents.

Nonrestorative sleep scale: a reliable and valid short form of the traditional Chinese version

Purpose

Previous research has suggested the essential unidimensionality of the 12-item traditional Chinese version of the Nonrestorative Sleep Scale (NRSS). This study aimed to develop a short form of the traditional Chinese version of the NRSS without compromising its reliability and validity.

Methods

Data were collected from 2 cross-sectional studies with identical target groups of adults residing in Hong Kong. An iterative Wald test was used to assess differential item functioning by gender. Based on the generalized partial credit model, we first obtained a shortened version such that further shortening would result in substantial sacrifice of test information and standard error of measurement. Another shortened version was obtained by the optimal test assembly (OTA). The two shortened versions were compared for test information, Cronbach’s alpha, and convergent validity.

Results

Data from a total of 404 Chinese adults (60.0% female) who had completed the Chinese NRSS were gathered. All items were invariant by gender. A 6-item version was obtained beyond which the test performance substantially deteriorated, and a 9-item version was obtained by OTA. The 9-item version performed better than the 6-item version in test information and convergent validity. It had discrimination and difficulty indices ranging from 0.44 to 2.23 and − 7.58 to 2.13, respectively, and retained 92% of the test information of the original 12-item version.

Conclusion

The 9-item Chinese NRSS is a reliable and valid tool to measure nonrestorative sleep for epidemiological studies.

Electronic supplementary material

The online version of this article (10.1007/s11136-020-02523-4) contains supplementary material, which is available to authorized users.

Study on the Relationship between Worker States and Unsafe Behaviours in Coal Mine Accidents Based on a Bayesian Networks Model

Unsafe behaviours, such as violations of rules and procedures, are commonly identified as important causal factors in coal mine accidents. Meanwhile, a recurring conclusion of accident investigations is that worker states, such as mental fatigue, illness, physiological fatigue, etc., are important contributory factors to unsafe behaviour. In this article, we seek to provide a quantitative analysis on the relationship between the worker state and unsafe behaviours in coal mine accidents, based on a case study drawn from Chinese practice. Using Bayesian networks (BN), a graphical structure of the network was designed with the help of three experts from a coal mine safety bureau. In particular, we propose a verbal versus numerical fuzzy probability assessment method to elicit the conditional probability of the Bayesian network. The junction tree algorithm is further employed to accomplish this analysis. According to the BN established by expert knowledge, the results show that when the worker is in a poor state, the most vulnerable unsafe behaviour is violation, followed by decision-making error. Furthermore, insufficient experience may be the most significant contributory factor to unsafe behaviour, and poor fitness for duty may be the principal state that causes unsafe behaviours.

Nonrestorative sleep scale: reliable and valid for the Chinese population

PURPOSE

To conduct a linguistic and psychometric evaluation of a Chinese version of the Nonrestorative Sleep Scale (NRSS).

METHODS

The Chinese NRSS was created from a standard forward-backward translation and trialed on 10 Chinese adults. Telephone interviews were then conducted with 100 adults, who completed the Chinese NRSS, the Pittsburgh Sleep Quality Index (PSQI), the Athens Insomnia Scale (AIS), the Center for Epidemiological Studies Depression Scale (CES-D), and the Toronto Hospital Alertness Test (THAT). A household survey was conducted with 20 subjects, followed by a confirmatory factor analysis (CFA), and a bifactor model was developed to evaluate the reliability and validity of the NRSS.

RESULTS

The bifactor model had the root mean square error of approximation (RMSEA), standardized root mean square residual (SRMR), and comparative fit index (CFI) of 0.06, 0.06, and 0.97, respectively. Convergent validity was shown from the moderate associations with PSQI (r = - 0.66, P < 0.01), AIS (r = - 0.65, P < 0.01), CES-D (r = - 0.54, P < 0.01), and THAT (r = 0.68, P < 0.01). The coefficient omega (0.92), omega hierarchical (0.81), factor determinacy (0.93), H value (0.91), explained common variance (0.63), and percentage of uncontaminated correlations (0.80) derived from the bifactor CFA supported the essential unidimensionality of NRSS.

CONCLUSIONS

The Chinese NRSS is a valid and reliable essential unidimensional tool for the assessment of nonrestorative sleep in the Chinese population.

Reduced sleep duration and history of work-related injuries among Washington State adolescents with a history of working

BACKGROUND

The relationship between sleep and occupational injury risk has not been adequately explored for working adolescents.

METHODS

Data were analyzed from the 2010 Washington State Healthy Youth Survey of 8th, 10th, and 12th grade public school students. Teens reported average school and weekend night sleep hours and history of work-related injury that received medical treatment. Multivariable logistic regression evaluated the association between sleep duration and occupational injury.

RESULTS

Of 4,144 working teens, 6.4% reported ever having an occupational injury. Teens who sleep ≤5 hr/school night had greater odds of a history of occupational injury than those sleeping 8 hr (OR:2.91, 95% CI:1.85-4.57). No significant association was observed for weekend night sleep duration.

CONCLUSIONS

Reduced school night sleep was associated with increased odds of work-related injury in adolescents. Long hours and late night schedules may contribute to decreased sleep time and potentially have other health and developmental impacts for youth.