Boundarylessness and sleep quality among virtual team members – a cross-sectional study from Germany


 Background

In the course of globalisation and digitalisation, new ways of work become increasingly prevalent. To remain competitive as an organisation, cooperation across time, place, and organisational boundaries becomes necessary. Virtual teamwork offers these advantages, but can also be both, an opportunity and a burden, for employees. The aim of this study is to gain first insights into job demands and resources in virtual teamwork to create a basis for deducing appropriate health promotion and prevention measures.
Methods

In this cross-sectional study, an online questionnaire was used to examine the relationship between boundarylessness as a job demand, psychological detachment as a personal resource, as well as perceived stress and sleep quality as health outcomes among 46 employees in virtual teamwork in Germany. Data collection lasted from October 2019 to January 2020. Validated scales were used for the questionnaire, except for virtuality. Due to insufficient operationalisation to date, a virtuality scale was developed based on the current state of research. The data were analysed with multiple regression analyses.
Results

The results show that virtuality and perceived stress impaired sleep quality of virtual team members in this sample. In contrast, successful psychological detachment from work was positively related to sleep quality. There were no significant results for boundarylessness. Virtual team members with managerial responsibility showed higher levels of psychological detachment.
Conclusion

The study provides first insights in the relationship between virtual teamwork and employee health in the German context. Further research, particularly on job demands in virtual teamwork, is needed to derive concrete health promotion and prevention measures.


Abstract Background
In the course of globalisation and digitalisation, new ways of work become increasingly prevalent. To remain competitive as an organisation, cooperation across time, place, and organisational boundaries becomes necessary. Virtual teamwork offers these advantages, but can also be both, an opportunity and a burden, for employees. The aim of this study is to gain first insights into job demands and resources in virtual teamwork to create a basis for deducing appropriate health promotion and prevention measures.

Methods
In this cross-sectional study, an online questionnaire was used to examine the relationship between boundarylessness as a job demand, psychological detachment as a personal resource, as well as perceived stress and sleep quality as health outcomes among 46 employees in virtual teamwork in Germany. Data collection lasted from October 2019 to January 2020. Validated scales were used for the questionnaire, except for virtuality. Due to insufficient operationalisation to date, a virtuality scale was developed based on the current state of research. The data were analysed with multiple regression analyses.

Results
The results show that virtuality and perceived stress impaired sleep quality of virtual team members in this sample. In contrast, successful psychological detachment from work was positively related to sleep quality. There were no significant results for boundarylessness. Virtual team members with managerial responsibility showed higher levels of psychological detachment.

Conclusion
The study provides first insights in the relationship between virtual teamwork and employee health in the German context. Further research, particularly on job demands in virtual teamwork, is needed to derive concrete health promotion and prevention measures.

Virtual teamwork as a new way of work
With the advent of new communication technologies, new forms of collaboration become increasingly prevalent. To address increasing globalisation and digitalisation, organisations implement project-based virtual teams which allows them to act very flexible on a volatile market (1). In a worldwide survey, 89% of 1,620 respondents from 90 countries reported to work on a virtual team (2). Virtual teams consist of members who collaborate across distances of space and time (3). In contrast to "traditional" teams, virtual team members are distributed among different locations, collaborating interactively based on a common task and/or goal (3,4) and are thus interdependent and share responsibility (5). Their communication is based on information and communication technologies (ICT), such as emails or video conferences (3). The transition from "traditional" to virtual teamwork is considered to be gradual rather than dichotomous i.e., teams may adapt higher or lower degrees of virtuality (3,5). They might also assume a hybrid shape, working face-to-face from time to time as well as never meeting each other in person (3,6). Examples of virtual teams range from team members in different departments or cities to intercultural, transnational or globally dispersed teams with members from different companies (4,7).
Parallel to these trends, another development is emerging that primarily affects employees, but also organisations, the national economy and community: since 2008 the number of mental disorders among employees has been increasing by 64.2% and, along with muscoskeletal disorders, has become the main cause of absenteeism and unemployability (8). The cost of mental disorders alone amounts to 44.4 billion euros per year in Germany (9). This development includes virtual team members. Previous studies on virtual teamwork mainly focussed on challenges and job demands, assuming that working conditions in virtual teams are more stressful than in collocated teams (10).
Despite the growing media and research attention for occupational health, the adaptation of mental health issues in the context of virtual teamwork has been scarce in research up to now (11). Although a few researchers have addressed both, challenges and job-related health outcomes in virtual teamwork (11)(12)(13)(14), but a dearth of research remains.

Study aims
To fill this void, the aim of this study is to gain first insights into job demands and resources as well as resulting health outcomes in virtual teamwork. These first insights may provide a starting point for the deduction of adequate health promotion and prevention measures in the context of virtual teamwork. The rapidly increasing implementation of virtual teams worldwide highlight the relevance of this study.

Theoretical background
We based this study on the theoretical framework of the Job Demands-Resources Model (JD-R Model) (15). This model was chosen because it extended the ideas of the job demand control model (16) and the effort-reward imbalance model (17), and includes both, demanding and beneficial aspects and processes of employees in their working environments (15). One main advantage of the JD-R Model lies in its adaptability and applicability to numerous occupational settings (18) as a myriad of empirical studies based on this theoretical framework show (19). The JD-R Model considers aspects of the job that require sustained effort associated with physiological or psychological costs, potentially triggering a health-impairing process that predicts psychosomatic health complaints. But the model also considers resources lying in the job itself or the person practising it. While job demands are negatively associated with health outcomes, job and personal resources are positively related to them and may help employees to cope with job demands (19). A high level of resources may also lead to higher motivation and keep strain on a medium level. Moreover, resources can serve as a buffer for job demands, reducing psychological costs and stimulating personal growth, learning, and development (20,21). To reach our objective of gaining insights into mental health among virtual team members, we examined boundarylessness as a highly prevalent job demand in virtual teamwork, and investigated psychological detachment as a personal resource to cope with this demand. Perceived stress and sleep quality were assessed as health outcome variables. Additionally, in the style of the theoretical framework, perceived stress was examined as a mediator between boundarylessness and sleep quality.

Boundarylessness in virtual teamwork
Although virtual teamwork promises many advantages, such as high flexibility, virtual team member face particular challenges due to their working conditions (11)(12)(13)(14). Not only do they depend on ICT and lack regular face-to-face contact, working across geographical distances and time zones can lead to expectations and practice of permanent availability among virtual team members (6).
Consequently, virtual team members have decreased possibilities to manage their work-life boundaries, thus personal time and phases of recovery (22). This boundarylessness refers to both, time and space (23). Facilitated by digitalisation, this can easily lead to an intrusion of work life into private spheres (23,24). There is evidence that permanent availability, as one aspect of boundarylessness and frequent ICT usage, creates stress among employees (14,25). Scientific literature refers to the inability to cope with new technologies as "digital stress" which is associated with health impairments and sleep disturbances (26). Sleeping troubles are not only associated with perceived stress, but also with characteristics of our globalised, highly digital and flexible "24-h society" (27) which are reflected in virtual teamwork. Their particular working conditions make virtual team members especially vulnerable to experience boundarylessness (28). Based on these findings, we formulate the following hypotheses:

Hypothesis 1:
There is a significant negative relationship between boundarylessness and sleep quality.

Hypothesis 2:
There is a significant positive relationship between boundarylessness and perceived stress (H 2a ) and a significant negative relationship between perceived stress and sleep quality (H 2b ).

Perceived stress partially mediates the relation between boundarylessness and sleep quality (H 2c ).
Proceeding from recent findings, we assume that virtuality rather poses a challenge to team members (10). There is first evidence from qualitative research that virtual teamwork is associated with stress (13). Consequences of stress range from somatic and somatoform to mental disorders (29). The association of sleep disturbances with digital stress and flexible working hours as well as their high prevalence of up to 42% among German employees (26,30) lead to the third hypothesis:

Psychological detachment in virtual teamwork
Especially when working "anytime anywhere" (31), mental disengagement from work-related duties becomes an important personal resource (32,33). Psychological detachment is one aspect of recovery experiences and describes the act of leaving work not only physically, but rather mentally (34). A lack of psychological detachment is associated with adverse health outcomes and reduced well-being (35), such as perceived stress (36) and diminished sleep quality (37). Recent findings highlight the relevance of psychological detachment as a personal resource to cope with boundaryless work and sleeping problems (38). Therefore, we assume that psychological detachment can be an important resource and coping mechanism for virtual team members. Based on these findings, we formulate the following hypothesis:

Hypothesis 4:
There is a significant negative relationship between psychological detachment and perceived stress (H 4a ). The ability to detach from work moderates the relation between boundarylessness and perceived stress in such way that psychological detachment attenuates the relation between boundarylessness and perceived stress (H 4b ). The ability to detach from work moderates the relation between boundarylessness and sleep quality in such way that psychological detachment attenuates the relation between boundarylessness and sleep quality (H 4c ).
The conceptual model of all formulated hypotheses is provided in Figure 1.

Sample and procedure
The study was conducted as a cross-sectional study, using an online questionnaire. Participants were recruited and the data were collected between October 2019 and January 2020. The sample was generated incidentally, without stratification or random selection. No grouping, such as a control group, was performed. Links to the online questionnaire were e-mailed to the contacted organisations and then internally forwarded to virtual team members. Participants were included in data analyses based on the following inclusion criteria: (1) virtual team members, (2) from Germany, (3) who worked as employees, (4) had work experience of at least one year, and (5) worked full time (at least 35 hours per week). Virtual team members were defined by working at different sites, collaborating based on ICT, and meting their virtual team members not more than once a week face-to-face.
Participants were recruited based on a list of IT companies provided by the chamber of commerce and a research of organisations in Germany deploying virtual teams i.e., predominantly medium-sized and large companies, via professional social networks, mailing lists, and online communities.

Data measurement
Based on the JD-R Model (15) and our hypotheses, boundarylessness was assessed as a job demand and independent variable. Virtuality and psychological detachment were examined as independent variables and moderators on the relationship between boundarylessness and the two outcome variables perceived stress and sleep quality. Perceived stress was also investigated as a mediator between boundarylessness and sleep quality, as shown in Figure 1. The data were collected based on self-reports in an online questionnaire, using a secure German online survey collection service. All surveys contained anonymous data only. Table 1 provides an overview of the main variables and their measurement. Note. IV = Independent variable. DV = Dependent Variable.

Sociodemographic and workplace variables
Self-constructed as well as already established items were used to assess job category (47), industry (48), job title, professional work experience (49), size of the organisation (50), type of employment, management responsibility (51), working hours, project work (52), age, gender, nationality, federal state, and education level (48).

Job demands
Boundarylessness was assessed using the reliable and validated boundarylessness subscale of the "Over how many different sites are you and your virtual team members distributed?" on a scale from 1 = we all work at the same site, 2 = two different sites, 3 = three different sites, 4 = four different sites, 5 = five or more different sites, also adapted from (41).
"How far does the majority of your virtual team members work away from you?" on a scale from 1 = in the same building, 2 = in the same city, 3 = in another city in the same country, 4 = in a different country, 5 = on a different continent, adapted from (40).
An additional "virtual job demands scale" of 13 items was developed to examine specific job demands of virtual team members based on previous research (11). These items were not included in the operationalisation of virtuality or regression analyses, but analysed for descriptive purposes only.

Personal resources
The psychological detachment-subscale of the reliable and well-validated Recovery Experience Questionnaire (34)

Health outcomes
We assessed perceived stress using the reliable and well-validated Perceived Stress Scale (45)

Statistical analyses
Initially, data were checked for plausibility, revealing on suspicious cases. Single items were recoded, where necessary, and scales were built. Before testing our hypotheses, we identified whether the assumptions for multiple regression analysis testing were met. Apart from a lack of normality and homoscedasticity for some variables, this assumption could be confirmed.

Descriptive statistics of the sample
After three months of recruitment, a sample size of N = 62 completed questionnaires was reached.
Cronbach's alphas are listed in parentheses on the diagonal.

Descriptive statistics of virtual job demands and health promotion offers
We also evaluated job demands other than boundarylessness using another self-developed scale as well as free text answers. Six participants reported specific job demands, such as a need for clear and measurable objectives, lack of social exchange, availability and high discipline, as well as different levels of media skills and technological equipment among virtual team members. Results from the descriptive analysis of the virtual job demands scale are provided in Table 4. Note. N = 46. All scales are five-point Likert scales, ranging from one to five.

Relationships between boundarylessness, virtuality, psychological detachment, and health outcomes
Results from multiple regression analyses are provided in Table 5 and Table 6.

Differences in degrees of virtuality
In addition, we conducted median-split t-tests to examine differences between groups among the sample. Splitting the data into higher and lower degrees of virtuality revealed that those 50% of participants who reported a higher degree of virtuality in their teamwork also reported significantly

Differences in levels of psychological detachment
We also found differences in the levels of psychological detachment between participants with

Discussion
The objective of the present study was to examine boundarylessness as a virtual job demand, psychological detachment as a personal resource, and perceived stress and sleep quality as related mental health outcomes among virtual team members in Germany. The results revealed significant associations of virtuality, psychological detachment, and perceived stress with sleep quality. The findings indicated potential negative effects of virtual teamwork as well as beneficial effects of psychological detachment on employee sleep quality.

Experience of virtual job demands
Occupational characteristics of the sample show that participants mostly worked on virtual teams within the same time zone. Although they reported some cultural and linguistic differences, they did not seem to perceive them as particularly demanding. Results from our self-developed virtual job demands scale indicate that the restricted possibility of social exchange and difficulties of socially integrating virtual team members concerned participants the most. Free text answers support this finding. However, the majority of participants were satisfied with the communication and collaboration within their virtual teams.

Relations between boundarylessness, virtuality, psychological detachment and sleep quality
Although the results do not support our hypothesised relation between boundarylessness and sleep quality, we found a significant negative relation of virtuality and self-reported sleep quality. This finding suggests that virtual teamwork may impair sleep quality and supports assumptions of previous studies (13,57). Since boundarylessness was not significantly related to virtuality, and virtuality was not significantly related to perceived stress, an explanation for the negative association with sleep quality remains open. Considering the sample size of this study, further research will be needed to identify other explanations. The application of longitudinal designs in future research could provide a deeper understanding of these relations.
Results also revealed that psychological detachment from work can be a valuable resource for virtual team members as it was positively related to sleep quality. This study therefore transferred already existing evidence of this relationship to the context of virtual teamwork (58,59). This finding can be particularly relevant to deduce prevention and health promotion measures in the future.
As part of our mediation hypothesis, we also found support for a positive relation between perceived stress and sleep quality among virtual team members. Again, this relationship supports evidence from previous research (26,60) and suggests its applicability to the specific working context of virtual teamwork. Possible consequences of enduring insufficient sleep highlight the relevance and urgency for further research on health outcomes in virtual teamwork (61,62). The fact that only about half of all participants reported that their employer provides health promotion offers emphasises the urgent need to develop appropriate measures for virtual team members to facilitate and support health promotion.
Relations between job demands, personal resources and perceived stress Contrary to our hypotheses, boundarylessness as a job demand was not related to perceived stress or sleep quality in this study. Reasons for these results may lie in the characteristics of the sample. The descriptive statistics indicate that the majority of virtual team members in this sample did not collaborate across large geographical distances or time zones. Asynchronicity resulting from such collaboration may have amplified experienced boundarylessness, as previous research suggests (41).
Although a qualitative Finish study found perceived stress among virtual team members, was virtuality was not found to be directly related to perceived stress in the present study. Another explanation could be a self-selection bias. Possibly, employees only work on virtual teams when they feel attracted to such working conditions or experience high flexibility as beneficial rather than demanding (63).
We did not find support for the predicted mediation of perceived stress. However, the lack of significance of most of the direct paths between the variables explains this finding (64).

Differences in degrees of virtuality, boundarylessness and psychological detachment
Post hoc median split analyses revealed that participants working in teams with a high degree of virtuality (e.g., long geographic distances between team members) perceived a stronger blending of work and private life whereas participants working in teams with a lower degree of virtuality (e.g. frequent or regular face-to-face meetings with team members) perceived less boundarylessness. This finding supports the assumption that virtual teamwork affects boundaries between work and private life (28).
Furthermore, participants perceiving high levels of boundarylessness reported lower psychological detachment. These results indicate that virtual team members who experience higher levels of boundarylessness also find it more difficult to disengage from work in their free time. This finding again highlights the urgency of developing prevention and health promotion measures for virtual team members, since higher levels of boundarylessness require even better psychological detachment to deal with work during leisure in a healthy way (32).
Interestingly, higher levels of psychological detachment were found among virtual team members with managerial responsibility. Therefore, it can be assumed that employees have greater difficulty to distance themselves from work during their free time whereas managers set a good example by detaching from work more successfully. This result is surprising because it contradicts Latniak's (2017) finding of higher amounts of burnout among project supervisors compared to employees in virtual contexts (65). Further research on virtual teamwork should, therefore, examine the role of health-oriented leadership and self-care in virtual teams (66).

Strengths and limitations
This study was the first quantitative study to apply an adapted version of the JD-R Model to the context of virtual teamwork in Germany. Our results provide first insights and contribute to obtain a better understanding of specific job demands, resources, and health outcomes among virtual team members to improve working conditions and promote employee health. Given the challenge of operationalising virtuality, this study took a chance to provide an instrument which considers both, key elements of the definition of virtual teams as well as contemporary ways of team communication.
Considering the reliability of this scale in this study, the challenge of developing a measurement assessing virtuality as it is currently implemented seems to last for future research. Another limitation of this study is the cross-sectional design, providing only a snapshot, but no opportunity for the interpretation of causal relationships. Self-reports may also affect objectivity in this study but were considered the most feasible way to obtain data. Moreover, we did not include a control group of "traditional teams" to compare the results of virtual teams to. Since the sample is relatively small and does not necessarily represent virtual teamwork in general, external validity of the results is limited.
In addition, the dearth of research addressing health in virtual teamwork provides a very limited base of literature for a discussion of our results. Therefore, comparable working conditions, such as mobile or telework, need to be adduced as well. The results therefore need to be interpreted cautiously.
Practical implications and future research It may be also helpful to establish binding rules of communication and documentation (11). Individual support could be provided through feedback conversations and coaching (71).
For further research it may be worthwhile to test especially boundarylessness in another quantitative study of a larger scale or longitudinal research design again since it did not appear as a significant job demand in this study. Future research may also want to examine other possible virtual job demands, such as technological stressors, coordinating efforts, conflict susceptibility, or information overload (6,11,72).
Operationalisation of virtuality remains a central challenge of future quantitative research, whether to rely on one single item (73) or on complex indices (41). The approach of including different media channels, frequency of usage, face-to-face meetings, spatial distance, distribution, and isolation, has not proven to be reliable in this study. More generally, the results challenge some fundamental ideas of the definition of virtuality.
Another possible explanation could be obtained by examining self-regulation as an intervening variable that might reduce perceived stress (74). Although it is important to investigate job demands and stressors, a focus on resources and coping strategies, such as resilience (75), will be necessary to deduce practical implications and develop concrete and target group-specific health promotion measures.
Finally, leadership in virtual teams has been addressed by researchers in the past already (76,77), but associations between leadership behaviour and employee health in virtual teamwork still need to be further examined (11). First studies indicate that appreciative leadership was perceived as a resource among virtual team members (71).

Conclusions
This study was the first quantitative one to apply the JD-R Model to the context of virtual teamwork in Germany. The results provide new information on job demands, personal resources, and health outcomes among virtual team members. Considering methodological limitations, the data revealed a negative relation between virtuality and sleep quality, but psychological detachment was found a valuable resource to cope with demands from virtual teamwork. Differences in this coping strategy among managers and employees provide a basis for further research. The results highlight the relevance and urgency to deduce appropriate prevention measures for virtual team members. Germany (Ethic-Code LPEK-0061). The ethical aspects were in full agreement with the Helsinki declaration. Prior to data collection, all respondents were informed about the aims of the study and data confidentiality and gave written informed consent. All participants took part in the survey voluntarily.

Consent for publication
Not applicable.

Availability of data and materials
The data analysed in this study are not publicly available due to German national data protection regulations.

Figure 1
Conceptual model of formulated hypotheses.

Figure 2
Results from median-split t-tests. (a) Differences in degrees of virtuality, (b) differences in levels of boundarylessness, (c) differences among managers and employees.