In recent years, the rise of neoliberal economic policies and technological advancements has not only led to significant labor market changes such as increasing job polarization and instability, but also stimulated extensive discussions about their implications for employees’ health and wellbeing (Autor et al., 2006; Fernández-Macías, 2012). As a critical component of well-being (Reid et al., 2006), sleep quality has gained increasing attention in the trend of labor market changes. Prior research has shown that adequate and high-quality sleep is not only necessary for optimal daily functioning and overall health (Henry et al., 2013; Watson et al., 2015), but also is closely related to employees’ work engagement and productivity (Swanson et al., 2011).
In previous literature, ample research has focused on the negative impact of long working hours on sleep, while another stream of research has investigated the relationships between specific job quality indicators (e.g., job demands, job control, workload, and work-family conflict) and sleep quality (Linton et al., 2015; Magnavita & Garbarino, 2017; Van Laethem et al., 2013). However, there are important limitations of the previous research. First, while job quantity and job quality are important determinants of sleep, both streams of research have been largely running in separate tracks without engaging in a direct dialogue. Second, in the previous literature job quantity and job quality were often measured by a limited number of indicators, ignoring their multidimensionality. For example, while job quantity should include both objective (working time) and subjective (working time preference match) dimensions, job quality can also be measured from multiple disciplinary perspectives including economics, sociology, psychology etc. Third, previous research implicitly assumes that the effects of job quantity and job quality are independent from each other, overlooking their interactive effects on sleep. This could hinder a comprehensive understanding of the relationships between job quality, job quantity and sleep, thereby impeding the development of effective labor market policies.
To address the research gaps, the present study aims to accomplish three objectives by adopting the sixth wave of the European Working Conditions Survey (2015). Firstly, the study aims to employ a unified theoretical framework of job quantity and job quality and examine the relative importance of both for sleep quality. Secondly, drawing on literature from various social science perspectives, this study aims to use a wide range of indicators to measure job quantity (including subjective and objective working time) and job quality (including eight job quality indicators from multidisciplinary theoretical perspectives). In doing this, we are able to compare the relative significance and impact of each job characteristic on sleep quality. Thirdly, the study seeks to understand the potential interplay between job quality and job quantity in shaping sleep quality. This will contribute to the discussion about the role of job quality in light of the trend of shorter working hours across the developed countries.
By accomplishing its three objectives, this study has significant theoretical and practical implications in three ways. Firstly, it contributes to the existing literature in the sociology of work by adopting multidimensional concepts of job quantity and job quality and providing a comprehensive understanding of how various job characteristics influence sleep quality. Second, this study offers a comprehensive investigation of the interaction between job quality, job quantity, and sleep quality. This deepens our understanding of the relative importance of job quantity and job quality, especially in the context of shorter working week across Europe. The findings shed light on further policy directions by providing a more holistic analytic framework of work and health. Third, the study’s findings have practical implications for labor market policies and the creation of a supportive workplace environment that fosters better sleep quality and mental health for employees. This may lead to more effective policies to address work-related stress and promote a favorable work-life balance.
Literature
Effects of job quantity on sleep quality
The latent deprivation model emphasizes the significance of employment in shaping an individual’s overall well-being, as it provides various latent functions such as time structure, purposefulness, participation, and shared experiences (Jahoda, 1982). Job quantity research builds on this model and proposes two directions to explore the relationship between employment and sleep quality/mental health. The first research direction focuses on the association between overemployment and poor sleep quality. Studies have demonstrated that long working hours increase the risk of sleep disturbances and inadequate sleep (Bannai & Tamakoshi, 2014; Barnes & Drake, 2015). Understanding the impact of job quantity on sleep quality is essential for developing effective labor policies and promoting employee well-being.
In contrast, another research strand aims to investigate the impact of underemployment on employees’ sleep quality/mental health. Studies have suggested that involuntary part-time work can have negative effects on the mental health of employees (Angrave & Charlwood, 2015; Heyes et al., 2017; Kamerāde & Richardson, 2018). This is because working fewer hours than desired may prevent employees from acquiring various financial and social benefits associated with employment, such as social status, identity, and interaction, which can lead to mental health problems. Additionally, underemployment may result in poverty, which has been associated with poor sleep quality. Previous research has demonstrated that individuals with low income and low socioeconomic status are more likely to experience poor sleep quality (Hale & Do, 2007).
Moreover, previous studies often adopt arbitrary standards to categorize work hours without considering the match and mismatch between actual and preferred work hours. This oversimplification of the relationship between job quantity and sleep quality limits the validity of previous findings. Thus, to address these gaps in the literature, the present study incorporates measures of work hours and work hour match simultaneously to provide a more comprehensive understanding of the relationship between job quantity and sleep quality. Moreover, the study also employs both subjective and objective measurements of job quantity to further investigate the interaction between job quantity, job quality, and sleep quality.
Effects of job quality on sleep quality
The emerging field of job quality has recently developed multidimensional indices based on a literature foundation from various social science disciplines. The present study employs a unified analytic framework of eight job quality dimensions, namely earnings, skill and discretion, physical environment, social environment, prospects, work intensity, working time quality, and job meaningfulness. Table A1 (in the appendix) summarizes the important dimensions of job quality related to mental health, and their theoretical backgrounds. Since sleep quality is a critical predictor of mental health, this study seeks to analyze the impact of the eight aforementioned dimensions of job quality on sleep quality drawing on relevant literature in the fields of job quality and mental health.
Earnings
The economic approach emphasizes earnings as a critical aspect of job quality, affecting employees’ sleep quality for two reasons. Firstly, income levels have been found to be significantly correlated with sleep duration, with lower income levels associated with both shorter and longer sleep duration. Additionally, studies have shown that people with low socioeconomic status, such as the black minority group in the US, tend to have poorer sleep quality. Secondly, financial strain and earning deprivation can negatively impact people’s ability to control their lives and undermine their mental health (Fryer, 1986). Empirical evidence suggests that lower income, financial strain, and a lack of material possessions are associated with decreased mental health, as indicated by common mental disorders (Reading & Reynolds, 2001). Moreover, as sleep quality is a component of mental health, it is believed that earnings significantly affect sleep quality. Given the widely recognized importance of earnings for sleep quality, it is crucial to include earnings into the job quality framework and compare its relative significance.
Skill and discretion
The traditional sociological perspective emphasizes the importance of skill use and autonomy, which is one critical dimension of job quality. However, the relationship between skill and discretion and sleep quality is mixed. Some studies suggest that individuals who engage in regular intense physical training or practice music for extended periods may experience better sleep quality (Driver & Taylor, 2000; Lauderdale et al., 2008), and autonomy is believed to promote sleep quality (Knudsen et al., 2007). In contrast, individuals who engage in high levels of cognitive activity or creative work may experience poorer sleep quality due to work demands and work-family multitasking (Schieman & Young, 2010). The demands of creative work may offset the hypothesized resource benefits of creative work for work-family conflict, leading to a negative impact on mental health. Therefore, this study will revisit the relationship between skill and discretion and sleep quality based on the mixed results of previous studies.
Physical environment
The occupational medicine perspective highlights that the physical work environment is an important dimension of job quality. Environmental health science research has shown that the physical work environment can contribute to the deterioration of mental health (Briner, 2000; Smith, 1991). In addition, prolonged exposure to noise has been identified as a significant cause of hearing loss, which can negatively impact mental health (Basner et al., 2014; Fellinger et al., 2012). As sleep quality is a critical measure of mental health, it is reasonable to involve the physical environment as one job quality index and evaluate its importance with other indicators.
Social environment
The radical and behavioral approach emphasizes industrial democracy, participation, and work organizations, and hence the social environment is another important dimension of job quality for employees’ sleep quality. Studies have consistently shown that social support and positive workplace relationships are associated with better sleep quality, which may be due to the positive emotional and physiological effects of social support (Ong et al., 2006; Troxel et al., 2010). In contrast, social isolation and negative stressors in the workplace can lead to poorer sleep quality and related health problems (Cacioppo et al., 2002). Therefore, the social environment should be included into the job quality framework when assessing the effects on sleep quality and its comparative significance can be indicated in this study.
Prospects
The institutional approach argues that contract status, employment stability, and career prospects are critical indicators of job quality. From the perspective of occupational medicine, job security is a significant source of stress that can have severe impacts on employees’ sleep quality (T. J. Kim & von dem Knesebeck, 2016; Mai et al., 2019). In addition, career development is a key component of an individual’s mental health and well-being. One study found that individuals who perceived that they had control over their careers experienced lower levels of anxiety and depression (Miller & Rottinghaus, 2014). Since sleep quality is a critical component of mental health, it is sensible to include prospects when predicting job quality’s impacts on sleep quality.
Work intensity
The work-life balance approach highlights work intensity as one critical dimension of job quality that is assumed to be associated with employees’ sleep quality. Studies have consistently shown that work intensity and job demands have a negative impact on employees’ sleep quality, where low job control and a lack of social support further exacerbate this relationship (Berset et al., 2011; Knudsen et al., 2007). Work-family conflicts and role conflicts also contribute to poor sleep quality, highlighting the importance of balancing work and family responsibilities (Burgard & Ailshire, 2009; Williams et al., 2006). Therefore, this study will consider work intensity as one crucial dimension of job quality and compare its significance with other indicators.
Working time quality
Working time quality is another important dimension of job quality based on the work-life balance approach. Working time quality, including shift work and non-standard work schedules, has been shown to significantly affect workers’ sleep quality (J. Kim et al., 2020). Several studies have demonstrated that shift work and night-time work are associated with shorter sleep duration, more sleep disturbances, insomnia, excessive sleepiness, and other sleep disorders (Drake et al., 2004). These effects are particularly prominent in healthcare workers, police officers, firefighters, and other professionals who work in emergency response systems and high-stress environments (Cropley et al., 2006; Garbarino et al., 2019). Acute job demands and job stress are also linked to poor sleep quality in these groups. Thus, working time quality is an important component of the present study’s framework of job quality, whose relative importance can also be assessed.
Meaningfulness
The classical sociology perspective emphasizes job meaningfulness as another important dimension of job quality indices, which may affect employees’ mental health and well-being. For example, Bakker et al. (2014) showed that a sense of fulfilment and work engagement, as a form of job resource, predicted better mental health. In addition, another qualitative study also demonstrated that work meaningfulness was associated with improved well-being and strengthened self-identification (Leufstadius et al., 2009). Since sleep quality is a critical component of mental health, work meaningfulness should be an important dimension of job quality and its relative significance is of great interest.
Interaction effects between job quantity and job quality on sleep quality
The impact of job quantity and job quality on employees’ sleep quality is a crucial area of investigation, given its implications for employee well-being and productivity. To gain a better understanding of this relationship, researchers have drawn upon the Vitamin Model (1987), which provides a comprehensive framework for examining the influence of job characteristics on employee well-being. The Vitamin Model identifies twelve job characteristics that affect employees’ satisfaction and well-being, including personal control, interpersonal contact, externally generated goals, skill use opportunities, variety, social position, and supportive supervision. Among these characteristics, interpersonal contact is particularly relevant to the impact of job quantity and job quality on sleep quality. Previous research has demonstrated that positive interpersonal relationships at work can enhance sleep quality and well-being, while conflict-ridden relationships have adverse effects. Moreover, job demands and job resources also play a role in sleep quality. For instance, high workload can have a negative impact on sleep quality, while social support from colleagues and supervisors can have a positive effect.
The concept of workplace “vitamins” has been introduced to describe job characteristics that are essential for maintaining good sleep quality and their optimal dosages. Similar to vitamins in the human body, the right amount of each workplace vitamin is crucial, as an excess or deficiency of any particular vitamin can have negative effects. While previous research has focused on job quality or job quantity separately, the interplay between the two has been relatively unexplored. According to Warr’s vitamin model, varying dosages of job quality can affect an individual’s sleep quality, and the combination of job quality and job quantity may also exert effects. For example, having a high-quality job with a low workload may positively impact sleep quality, while a low-quality job with a high workload may have a negative impact. However, a job with high job quality and a moderate workload may be optimal for good sleep quality.
Despite the importance of this issue, research on the relationship between job quantity and job quality has been limited. Although most studies have focused on underemployment and zero-hours contracts, some research suggests that the correlation between working hours and job quality dimensions is not straightforward or linear, indicating that their interaction can result in diverse outcomes. For example, shorter working hours can reduce work intensity when employees have control over their schedules, while employer-led shorter working hours are often associated with higher work intensity (Piasna, 2018). Given the mixed results of previous studies, the primary aim of this study is to explore how the “dosage” of job quality interacting with job quantity affects sleep quality.
Research gaps and questions
There has been a lack of communication between research on job quantity and job quality, with both areas largely running in separate tracks without engaging in direct dialogue. This disconnect is unexpected given that both areas are concerned with employees’ sleep quality, and the failure to integrate these areas could result in misguided policy recommendations. Therefore, it is crucial to integrate both job quantity and job quality, as well as their combined effects on employees’ sleep quality, into academic studies and policy implications.
The present study aims to fill these research gaps and contribute to the literature in three main ways. Firstly, while prior research has examined the relationship between job characteristics and sleep quality, few studies have simultaneously examined the impact of job quantity and job quality on sleep quality. In other words, limited studies have explored the relative importance of job quantity and job quality when more emphasis is placed on long working hours. Therefore, this study employs a unified analytical framework of job quantity and job quality with exhaustive indicators to investigate their relative importance. This study sheds lights on the multidimensionality and significance of job quality, and investigates how good and bad jobs differ in their impact on sleep quality.
Secondly, prior research has often measured job quantity and job quality by a limited number of indicators, ignoring their multidimensionality and comprehensiveness. Furthermore, the relative importance and impact of each job characteristic remain questionable. Therefore, this study revisits the influence of job quantity on sleep quality by including objective (working time) and subjective (working time preference match) measurements at the same time, rather than adopting an arbitrary standard of over- and under-employment. Moreover, the present study employs eight indices to measure job quality based on multiple disciplinary literature. Understanding the relative importance of each job dimension could help employees improve their sleep quality more strategically and effectively.
Thirdly, this study aims to examine the interplay between job quantity and job quality and their impact on sleep. Since job quality is inevitably associated with working time, it is crucial to investigate the joint effects of job quality and job quantity on sleep. The degree of job quality may also determine or moderate the effects of job quantity on sleep. However, previous research has paid little attention to the interaction effects of job quality and job quantity on sleep quality. Understanding the interaction between job quality and job quantity on sleep quality can provide a more accurate assessment of the impact of different job quality indicators, independent of job quantity and other confounding factors. Therefore, this study fills a critical gap in the literature by examining the joint effects of job quality and job quantity on sleep quality and further highlighting the importance of job quality.
Therefore, the aim of this study is to investigate the independent and interactive effects of job quality and job quantity on employees’ sleep quality. The study aims to answer two primary questions:
- What is the significance of job quality indicators and job quantity, including work hours and the match between actual and preferred working hours for the sleep quality of employees?
- To what extent does the impact of job quality depend on job quantity? Specifically, does the effect of job quality decrease for employees with short, long, or unmatched working hours?