Introduction

In today’s environment, it is typical for someone to have a job. When someone holds a job, people are expected to show loyalty through long-term dedication. Downsizing, restructuring and layoff of employees have become more prevalent norms in organisations (Holbeche, 2015). The rapid advancement of science and technology contributes to generating new knowledge. Over the last few decades, numerous jobs focused on producing, processing and disseminating knowledge and information have surfaced. Initially, these roles were found exclusively within the high-tech and information and communication service industries, but they have since spread to encompass all other sectors (Satish et al., 2023). As a result, employees must now take an interest in their growth and potential for employment (Holbeche, 2015). One approach an employee adopts is moonlighting, which involves simultaneously holding multiple jobs (Kisumano & Wa-Mbaleka, 2017). Moonlighting occurs when a person does multiple jobs simultaneously (Husain, 2014). Moonlighting is referred to by various terms such as ‘multiple job holding’, ‘dual job holding’, ‘second job holding’ etc. Moonlighting has become more common as people seek additional jobs alongside their primary job (Jefferson & Nithya, 2023).

Several theories and models have been used to explain moonlighting, such as relative deprivation theory, aspiration theory and work–leisure choice theory (Adjei, 2013; Baah-Boateng et al., 2013; Betts, 2004; Kisumano & Wa-Mbaleka, 2017). Betts (2004) categorises moonlighting into economic and dispositional approaches, with economic theory focusing on primary income. The dispositional approach finds two theories to define moonlighters: deprivation theory and aspiration theory. Deprivation theory defines moonlighters as socially and economically deprived, while aspiration theory identifies individuals with higher aspirations and drives to find new jobs. Two main definitions describe moonlighters (Boateng, 1996; Boateng et al., 2013). First, the point definition focuses on a specific point in time, defining individuals as moonlighters if they work multiple jobs in a specific reference period. However, it does not consider concurrent occupations, which may include temporary transitional jobs or individuals with no intention to keep both jobs. Second, the duration definition considers the entire period, defining individuals as moonlighters if they work multiple jobs continuously or intermittently (Shishko & Rostker, 1976).

Moonlighting has been widely investigated in various fields such as teaching (Magadley, 2021; Ngwenya, 2021; Sakyi & Agomor, 2021), healthcare (Bruns & Pilkauskas, 2019; Muruga & Vasiljeva, 2021), politics (Caria et al., 2023; Hurka & Daniel, 2018; Hurka et al., 2018), police (Lippert et al., 2019) and IT (Doucette & Bradford, 2019; Sharma et al., 2021) sectors. Shishko and Rostker (1976) were pioneers in studying multiple job holdings. They combined theoretical reasoning with real-world analysis to understand why people engage in moonlighting, which refers to working multiple jobs. They built the first theoretical model of moonlighting. Later, Schwarze (1991) expanded on their work by incorporating job quality into the model. Conway and Kimmel (1998) examined the connection between the amount of labour individuals contribute to their primary and secondary jobs. This study identified the motivations behind multiple job holdings and supported two main motives: ‘hours-constraints’ and ‘heterogeneous jobs’. The length of time individuals engage in multiple job holdings was examined in studies conducted by Marshall (2002) and Kimmel and Conway (2001). These studies consistently revealed that the ‘hours-constraint’ motive is the most common reason for moonlighting, as individuals seek additional jobs to meet financial needs or personal goals. Averett (2001) investigated gender differences in moonlighting behaviour and wages, finding that motives may not differ significantly between men and women, but how they navigate multiple job holdings can vary. The primary drive behind moonlighting is to earn additional income, which can impact consumer preferences and buying behaviours. The pandemic presented organisations with a chance to secure loyal customers. It was an opportunity for managers to integrate corporate social responsibility (CSR) into their brand-building strategies (Menaga et al., 2023). The researchers point out that employing event marketing, media monitoring and customer loyalty programmes as marketing tools can effectively foster customer loyalty. Media marketing, in particular, is critical during the pandemic (Tomar, 2023).

Moonlighting has garnered attention from researchers, employers and policymakers due to its implications for an individual’s work–life balance, financial stability and overall well-being. With the changing nature of work and evolving employment patterns, understanding the motivations, consequences and dynamics of moonlighting is crucial. Exploring the reasons why individuals choose to moonlight, the impact on their primary job performance, the challenges faced in balancing multiple jobs and the potential benefits and drawbacks are essential areas of investigation.

Hence, our article aims to find out the following research questions.

 

Q1. What is the overall publication trend in moonlighting research over time?

Q2. Who are the most influential authors and sources in this field?

Q3. Which journals, publishers and associations are the most influential in this field?

Q4. What are the emerging themes and research areas within moonlighting research?

Methodology

In this study, we conducted a bibliometric analysis and literature review (LR) to provide an overview of the moonlighting domain. Bibliometric analysis is an effective method for uncovering and pinpointing research gaps within the existing literature (Duhoon & Singh, 2023). First, we performed LR to gather the data for bibliometric analysis by defining the specific keywords to retrieve the data from the Scopus database. We searched for relevant information by using specific keywords in the Scopus database. Then, we carefully selected papers that matched our criteria, following a structured approach called the PRISMA method. To collect bibliographic information, we accessed the Scopus database and focused on articles published on moonlighting. We narrowed down our search by selecting specific categories that align with the current needs of businesses in the post-COVID-19 era. Next, we analysed the collected data using the bibliometric analysis technique. We used the Biblioshiny software of RStudio and the Bibliometrix package developed by Aria and Cuccurullo (2017) for bibliometric analysis. This allowed us to gain valuable insights from the articles related to moonlighting. Through our analysis, we discovered interesting patterns and trends in moonlighting research. We identified key authors who have contributed significantly, observed the number of papers published each year and explored the impact of different countries and authors. We also looked at collaborations between countries in this field. Bibliometric analysis will help us to identify the evolution of research themes and gaps that may guide future research scope in this area.

Defining Search Terms

In our bibliometric analysis, we employed a range of keywords to ensure a comprehensive search of the literature on moonlighting. These keywords included ‘moonlighting’, ‘multiple job holding’, ‘second job holding’ and ‘dual job holding’. By using variations of these keywords, we aimed to capture diverse aspects and perspectives related to moonlighting. By including these varied keywords, we sought to encompass different terminologies and expressions used in the literature to describe moonlighting. This approach helps to ensure that our search is inclusive and captures a wide range of relevant studies.

Search Delimiting Criteria

On 5 June 2023, we collected data for this study (Figure 1). The search query included terms such as ‘moonlighting’, ‘multiple-job holding’, ‘dual-job holding’ and ‘second-job holding’. We included the records spanning the last 45 years, from 1977 to 2023. Initially, the search yielded 1,770 references. To streamline the results and ensure the inclusion of highly relevant records, we further refined the search based on ‘source types’. We excluded records from irrelevant areas such as agriculture, biological science, medicine and mathematics. Instead, we focused on selected areas such as social science, economics and finance, multidisciplinary, business management and accounting, psychology, and art and humanities. We focused on these categories because our research primarily considers the business perspective of moonlighting. After applying these subject area refinements, the number of records was reduced to 392. Then, we refined the results based on the ‘document types’. We eliminated books and book chapters, including only articles, reviews and conference papers. This refinement narrowed down the records to 373. To ensure the feasibility of reading and analysis, we included papers available only in English. After implementing this language filter and all previous refinements, we were left with a final set of 362 documents (Table 1).

 

Figure 1. Screenshot of Search Query Used by Scopus Database to Retrieve Data.

 

Table 1. Bibliographic Data Retrieval Process.

Note: This table presents the steps incorporated to select the documents for bibliometric analysis.

 

Data Retrieval for Bibliometric Analysis and Systematic Literature Review

In the final set, we encountered a pool of 362 research works. To ensure clarity and maintain focus on the most relevant studies, we employed a rigorous process by using the PRISMA approach (Figure 2). First, we carefully analysed the keywords and abstracts of each article and eliminated 174 documents unrelated to this field. Then, the second stage of refining was performed after accessing the full-text papers, and those articles whose objectives did not match our study’s requisites were further eliminated. Some papers were inaccessible and thus eliminated from the study. Finally, we had 177 documents for bibliometric analysis and LR.

Result and Discussion

Year-wise Trends and Scientific Productivity

Figure 3 shows the annual production of articles, illustrating the research trend in publications since 1977. The figure demonstrates a consistent growth in the number of publications per year. On average, an annual growth rate of 3.97% indicates a steady increase in research activity. The year 2021 stands out with the highest number of publications, that is, 16 articles. This indicates a peak in research interest and activity during that year. Approximately 60% of the literature analysed in this study was published after 2009. Hence, it is evident that moonlighting has gained momentum after 2009. The period from 2011 to 2021 became the turning point where the number of publications increased.

 

Figure 2. Inclusion Exclusion Criteria for Retrieval of Data for Bibliometric Analysis Using PRISMA Approach.

 

Figure 3. Annual Productions of Articles Published on Moonlighting.

Note: This figure presents the distribution of the shortlisted articles based on the year of publication.

 

Furthermore, a notable growth in the publications can be observed from 2019 to 2021. This may be attributed to the impact of the COVID-19 pandemic. During this time, job uncertainty heightened, and employees faced numerous financial, emotional and health challenges. These circumstances likely heightened interest in moonlighting research.

Influential Source Analysis

The top 10 most influential journals that have made significant contributions to the field of moonlighting are shown in Table 2. Applied Economics is the highest contributor, with seven publications related to moonlighting. Its substantial presence in the field indicates its strong commitment to publishing research on this topic. Industrial Relations is ranked the second highest contributor with four publications. John Wiley & Sons is the publisher of three journals in the top 10 list, so John Wiley & Sons is the most contributing publisher in this field. The top journals listed in Table 2 exhibit good impact factors. Three of these journals have an impact factor above 5, indicating the quality and influence of the selected articles published within these journals. The citation analysis indicates the influence and impact of the publication in terms of an h-index and m-index. Applied Economics is the most influential source based on the citations analysis matrix. So, Applied Economics is a highly contributing and influential source in the field of moonlighting.

 

Table 2. Top Influential Journals, Their Influence and Impacts.

Note: This table lists the top 10 journals with the name of publisher, the number of publications (NP), the journal impact factor (JIF) and the impact indices (h-index, g-index, m-index) as per the Scopus database.

 

Table 3. Top Influential Authors, Their Impact and Influence.

Note: This table lists the top contributing authors on moonlighting with a high number of publications (NP), their current affiliations and the total number of citations (TC).

 

Table 4. Top Influential Articles, Their Authors and Impact.

Note: This table lists the top 10 articles with the highest total citations (TC), their year of publication and their authors.

 

Influential Author Analysis

The information about the most contributing authors on moonlighting is presented in Table 3. Jean Kimmel was the most productive and efficient author because she had the highest production and citations. Alexandros Zangelidis was the second productive author who wrote four documents with high citations. Arjun Singh Bedi, with two publications, is highlighted as an efficient author due to the highest average citation per year among top contributors. This indicated that their work had received many citations in the publication years. Furthermore, five authors had two publications each, demonstrating a notable contribution to the field. Four out of these five authors are from the United States, which aligns with the observation that the United States is among the most producing countries in the field of moonlighting.

Influential Document Analysis

Table 4 shows the top 10 documents that have made significant contributions to our topic. The paper titled ‘Wage Differentials Between the Public and the Private Sectors: Evidence from an Economy in Transition”, written by Arjun Singh Bedi and Vera Adamchik in 2000, had the highest number of citations. Jean Kimmel and Alexandros Zangelidis are two authors who wrote three documents, each with other authors, and received good citation counts. Table 4 shows Jean Kimmel as the most contributing and influential author in this field.

Influence and Collaboration Analysis of Affiliations and Countries

Affiliation analysis was conducted to study the contribution of significant universities and regions to our topic. Table 5 shows the top 10 universities based on the number of publications. The University of Aberdeen, located in the Netherlands, is the most influential affiliation, contributing the highest number of publications, that is, seven. Georgia State University from the United States follows closely, with the second-highest publications. The overall result of Table 5 indicates that universities in the Netherlands have shown significant contributions and have been at the forefront of publishing on this topic.

 

Table 5. Top 10 Influential Affiliations in Their Country and Impact.

Note: This table lists the top 10 affiliations with country and the number of publications.

 

Table 6. Top 10 Influential Countries, Their Impact, Influence and Collaborations.

Note: This table lists the top 10 countries with the high number of publications (NP) and their single-country publications (SCP), multiple-country publications (MCP) and total citations (TC).

 

Most Influential Country Analysis

Table 6 enlists the top 10 countries with the highest number of publications in the field of moonlighting. The United States is the top contributing country with the maximum number of publications, that is, 31. The United States is also a highly impactful country, having the highest total citations and a keen interest in country publications. Multiple country production (MCP) indicates collaboration among countries, with the United Kingdom at the top, with five multiple countries producing. The United States and Germany have four MCPs, but if we compare the ratio with total articles, the United States is ahead of Germany. Georgia has shown a keen interest in collaboration, as all four of its publications involve collaborations with other countries. Italy has four publications but no collaborations with other countries.

Content Analysis of Literature

A content analysis of the literature published in the last 10 years (2013–2023) was performed, and three clusters were identified based on common themes. These three clusters represented distinct themes and knowledge domains within the literature, providing valuable insights into the intellectual structure and prevailing research trends from 2013 onwards.

The cluster was organised according to themes identified through document analysis presented in Figure 4. These themes were divided into four parts: emerging, basic, motor and niche themes. The first cluster was formed based on the basic theme, including topics such as moonlighting and self-employment and factors related to multiple job holdings. The second cluster was established based on the motor and niche themes, incorporating specific factors such as job performance, work conditions and labour dynamics in moonlighting. The last cluster was created to focus on motor and emerging themes.

Cluster 1: Moonlighting and Multiple Job Holdings

Cluster 1 investigates moonlighting and multiple job holdings, exploring motivations, determinants and implications in various contexts. Most studies show moonlighting as a source of additional income for employees (Asravor, 2020; Preston & Wright, 2020; Sakyi & Agomor, 2020). These studies show that the first motive for moonlighting is financial. Both men and women engage in moonlighting to deal with the financial difficulties faced because of lower earnings from their primary occupation (Piasna et al., 2020). The central premise is that the earnings from the primary job are insufficient to meet individual, family or household needs. These studies revealed gender differences concerning the rationale for working in multiple jobs. Doucette and Bradford (2019) found that job hour constraints, a common reason for traditional moonlighting, motivated men to spend more time in secondary jobs to increase incomes, while women were motivated by insecurity in their primary jobs. Additionally, studies also explore the impact of moonlighting on organisational commitment (Khatri & Khushboo, 2014), work engagement (Peng et al., 2021), job satisfaction and burnout (Rasdi et al., 2021) and financial well-being (Quarshie et al., 2022). Bouwhuis et al. (2019) conducted a study in the Netherlands. They found no significant differences in health between multiple and single job holders, with multiple job holders experiencing less sickness absence. Magadley (2021) conducted a study in Israel that found work–family conflict among moonlighters, with women bearing a heavier burden. The cluster encompasses research from various geographical areas, including South Africa, Europe and the Czech Republic.

 

Figure 4. Clusters According to Documents.

Cluster 2: Job Performance, Work Condition and Labour Market Dynamics in Moonlighting

Cluster 2 focused on how people perform their jobs, their working conditions and how the job market behaves. It includes research on various professions such as teaching, IT, police and politics. One area of this cluster focused on how work conditions affect job performance. Ngwenya (2021) revealed that poor work conditions, including low remuneration and heavy workloads, negatively impact teacher performance, as inadequate compensation and excessive workload negatively affect job satisfaction. Better work conditions lead to fewer employee complaints as they become happier with their work conditions than the IT sector employees. It also reduces absenteeism and increases productivity (Roelofsen, 2002). Other studies revealed that a safe and comfortable workplace can significantly impact employee’s well-being and overall performance (Eluka & Okafor, 2014; Ogbo & Ukpere, 2013). Another aspect of this cluster explores the employment situation. It looks into unemployment rates, labour market flexibility and how these factors influence employee behaviour. Shishko and Rostker (1976) revealed that every rational worker who faced dissatisfaction with their current job’s working hours and wanted to maximise their utility might consider adding a second or third job. However, this possibility is feasible only when there is a very high level of flexibility in employment. Owusu (2005) indicated that civil service employees have the highest rate of moonlighting because they offer a very high level of flexibility in employment. Several studies have been done on moonlighting determinants; they have looked mainly at factors such as time constraints (Shishko & Rostker, 1976) and financial constraints (Guariglia & Kim, 2004). One more factor in employment security has considered the push factor of moonlighting (Nunoo et al., 2018; Renna & Oaxaca, 2006).

Cluster 3: Politics, Government and Public Policy

Cluster 3 revolves around politics, government and public policy. First, the cluster analyses citizen’s responses to politicians engaging in moonlighting. In many countries, including the UK, countries of the EU and Germany, Members of Parliament (MPs) are allowed to have other jobs, either paid or unpaid, alongside their roles in parliament (Agrawal & Knoeber, 2001). The permission for MPs to have sideline jobs varies from country to country, and each country’s parliament may have its own rules and regulations regarding this practice (Geys & Mause, 2014). Some professions that could create conflicts of interest were banned for MPs, such as lobbyists, consultants and those directly involved in industries (Allen, 2008). Another aspect explored in this cluster is public policy issues on health system development and employment security. In recent years, dual practice has become a prevalent trend in the healthcare industry, particularly among physicians, nurses, midwives and technicians (Gonzalez, 2004; Jan et al., 2005). The income disparity between specialists in the public and private sectors has been a critical driving force behind this practice, promoting healthcare professionals to explore opportunities in both domains simultaneously (Joyce & McGrail, 2014). One significant revelation from studies is that residents across various disciplines express a solid desire to moonlight to supplement their income, advance their education and foster greater independence and self-confidence (Jamshidi & Reilly, 2008; Matthews et al., 1998). Moreover, a comprehensive study indicated no difference in perceived quality of life or financial distress between residents who moonlight and those who do not (Bayat et al., 2018). These findings suggest that moonlighting does not compromise the well-being of healthcare professionals.

Future Scope

After thoroughly reviewing the existing literature, I see that this area has continuously grown. However, some gaps require further investigation through in-depth research. In existing literature, we observed that moonlighting practices have been studied in various professions, including healthcare, education and IT (Bruns & Pilkauskas, 2019; Doucette & Bradford, 2019; Magadley, 2021; Sakyi & Agomor, 2021; Sharma et al., 2021). However, there is a need to delve deeper into understanding the specific factors that drive moonlighting in each of these sectors and its implications on professionals and the industry itself. After reviewing, it was evident that moonlighting practices increased significantly after the COVID-19 pandemic, especially with the rise of remote work. Future research is essential to better understand the impact of digital transformation and freelance work on multiple job holdings. Most empirical studies used panel data from different points in time, so future studies may utilise another source of data collection, like primary data collected directly from the respondents through questionnaires, interviews, focus group interviews and thematic and sensitivity analysis, to have a broader understanding of the concept. Most studies focused on the financial and economic perspectives of moonlighting, and a few studies were oriented towards the behavioural aspects of moonlighting. So, future research could work on behavioural dimensions like work–life balance, motivation, quality of life, etc. Most studies used a quantitative research design that measures the panel data. Only a few studies used qualitative research design, so future researchers could use qualitative research design and pay attention to understanding people’s stories and experiences. Further, in the analysis of cluster 1, we assessed that the demographic variables directly impact moonlighting behaviour. So, future researchers should assess the impact of different demographic variables on employees’ moonlighting behaviour to determine the role of these variables in moonlighting.

Conclusion

The study synthesised existing literature on moonlighting using bibliometric analysis and LR. Key factors contributing to growth include workplace flexibility, curiosity-driven skill enhancement and quality of life.

In bibliometric analysis, we found that Applied Economics and Industrial Relations were the top journals in our lists. Jean Kimmel contributed maximum literature on moonlighting. The University of Aberdeen had the most influential affiliation, and the United Kingdom and the United States were highly producing countries.

Three clusters were extracted based on content analysis. Cluster 1 mainly focused on moonlighting motives, determinants and implications. Cluster 2 tested the impact of work conditions and labour market dynamics on employees’ job performance. Cluster 3 described the response of the public and government to moonlighting practices in different professions and addressed policy issues related to health system development. These clusters will help researchers to choose their area of interest for future studies. Lastly, we identified future research avenues to guide the researchers’ investigations.

Acknowledgement

The authors are grateful to the journal’s anonymous referees for their beneficial suggestions to improve the quality of the article.

Declaration of Conflicting Interest

The authors declared no potential conflicts of interest concerning this article’s research, authorship and/or publication.

Funding

The authors received no financial support for this article’s research, authorship and/or publication.

ORCID iD

Vandana Sharma  https://orcid.org/0000-0003-2013-3989