The present study suggested that there are time-lagged effects over a 2-year period, of WLC on NPS, as suggested in our first hypothesis. Furthermore, prospective effects of sleep problems on NPS were established, confirming the second hypothesis. Previous research supports these finding, as both WLC and sleep problems have been found to have negative effects on employee health (Doi et al.,
2003; Grant-Vallone & Donaldson,
2001). Frone (
2003) in his review on the effects of work-life conflict and work-life balance, concluded that work-life conflict affects psychological distress and mood disorders, self-reported poor physical health, and substance abuse in employees. Sleep problems have been associated with increased levels of sick leave, as well as with poor physical- and psychological health (Doi et al.,
2003). Since these modifiable factors have such a visible impact on employee health, and therefore come with a significant societal cost, workplace interventions may wish to target WLC and sleep, which may lower levels of reported pain as well as improving general employee health over time.
Furthermore, the suggested prospective relationships of WLC on NPS are mediated by sleep problems, as suggested by the third hypothesis. Hence, as a result of conflict between their work- and private life, employees may experience sleep problems, which may contribute to multisite musculoskeletal pain complaints and an increase in number of pain sites.
Finally, support did not significantly moderate the indirect effect of WLC on NPS, i.e. levels of support at work from both supervisor as well as coworkers have not been found to buffer the negative effects of WLC on sleep and number of pain sites, which means hypothesis four is not supported by the findings. However, previous studies suggest support may affect sleep problems individually (Akerstedt et al.,
2002). Although support may not be sufficient to substantially alleviate the aversive effects of work-life conflict on sleep and pain, it should be noted that it may still play a role in the work–pain relationship. A supportive supervisor who shows understanding of private life demands may for example be forthcoming in solutions when, often unplanned, private life commitments tip the balance. Support may relieve some of the worries employees may experience when work-related expectations are not met due to limited resources, for example, when an employee needs to leave early because of such home-life related engagements.
The present results provide insight into possible mechanisms through which psychological and social work factors may affect pain. It may be that the conflict between demands from work and home affect sleep because of their dual claim on common resources, e.g. time, and findings may be used in the developments of work interventions., since WLC, sleep, and support are all modifiable factors.
Limitations
Both support and WLC items come from the QPSNordic, a reliable and validated questionnaire (Dallner et al.,
2000). Items comprising the WLC scale included in the present study do not constitute a scale in the QPSNordic, rather they are two single items reflecting work–private life interactions. The support scale in the QPSNordic comprises more than the coworker- and superior support items included in the present study. The authors chose to focus primarily on work-based support. Sleep items do not compromise a scale, but have been measured together in other studies (Vleeshouwers et al.,
2016). What is more, all variables reflecting measures included in the present study show high correlations between items.
NPS appears to be stable across time, with little variance between baseline and follow-up measures. It is important to note that this does not mean no change on the individual level has occurred between the two time points. While the average change in NPS is moderate, individual levels of NPS may have fluctuated more than the sample level change reflects. High stability combined with baseline adjustment may affect analyses by making effects more difficult to detect.
Only a small number of participants experience high levels of conflict between work- and private life and/or low levels of support. These groups may have simply been too small to establish any effect if present. Since counterfactual mediation analysis relies on comparing groups, the absence of a moderated mediation effect of support could be due to a lack of statistical power. The fact that so few employees experience these ‘extremes’ in these work factors may be due to Norway’s relatively stable and modern workforce (Abendroth & den Dulk,
2011; Crompton & Lyonette,
2006). Moreover, Norwegian work culture is characterized by equality and flexibility, with a dual-earner model with both mother and father in paid work, and with extended childcare- and annual leave arrangements, and often with flexible working arrangements available (Kvande,
2009). When compared to other cultures, such as for instance the US, where gender roles in employment appear more visible and the man is often the breadwinner, and where rules and regulations are less forthcoming (Allen et al.,
2015), clear differences in levels of work–private life conflict are observed. In Norway, workers in full-time employment have an average of 15.5 h daily to spend on leisure and personal care, while workers in the US have 1 h less (OECD,
2015).
While the present study has shed some light on possible mechanism explaining relationships between WLC, and pain, more research is needed in order to improve our understanding of underlying mechanisms. Because of the 2 year time frame, it is possible that effects are transmitted through alternative causal chains, or that there are additional or alternative causes (Shrout & Bolger,
2002). Other factors are likely to play a part in the multifaceted relationship between work, sleep, and multisite pain. Depression caused by work-factors could affect sleep (Bonde,
2008), which in turn affects pain. Similarly, one could argue that appraisal and coping, exercise, and biomechanical exposures at work, may influence these complex relationships. The purpose of the current study was to investigate the role of sleep in mediating the relationship between work–private life conflict and pain. While we did have access to some information about mental health, we chose not to include this in the present analyses. While individuals experiencing mental distress could be more vulnerable to effects of work–private life conflict on sleep and/or pain, it may also be that the experience of WLC affects psychological status, which in turn may affect sleep and/or pain. Confounding is another possibility, if for instance distress affects both WLC, sleep, and pain. We chose not to include mental distress as a control variable since it would be unclear whether any impact on results would be due to effect modification, mediation, or confounding. Moreover, baseline adjustment for NPS should attenuate confounding if distress influenced WLC and NPS similarly across time. Nevertheless, the possible influence of distress should be kept in mind when interpreting results. Future studies may wish to address distress and other potential mediators and moderators that may be a part of the work–pain mechanism.
Organizations partaking in the study received feedback on all psychological and social work factors studied in the form of reports and presentations after each round of data collection. While it is possible that some companies chose to change some of their work practices based on feedback received after T1, no significant differences in WLC between T1 and T2 were found in post hoc analyses in the overall sample.
This study indicated that WLC affected NPS, partly through influencing sleep problems. Social support at work did not significantly moderate this relationship, but may still affect sleep problems and NPS. Although much is still unclear about causal mechanisms, workplace interventions have been shown to improve employee control, work–family conflict, and sleep (Olson et al.,
2015). Findings may be used towards the construction of workplace intervention initiatives that alleviate WLC and improve supportive behaviors in the workplace. One central implication for organizational practitioners is that in cases where work–private-life conflict cannot be avoided organizational support may be particularly important in order to alleviate undesirable consequences. When the bidirectional relationship between work and private life results in positive spillover, sleep may be improved (Williams et al.,
2006). Workplace interventions aimed at decreasing overtime work and spillover between employees’ private life- and work life, and to improve employees’ control over work and home balance, as well as improving communications and support mechanisms at work could significantly improve employee health and well-being, which in turn could benefit productivity and decrease sickness absence.