Aims: Past research has often neglected the sub-dimensions of work time control (WTC). Moreover, differences in levels of WTC with respect to work and demographic characteristics have not yet been examined in a representative sample. We investigated these matters in a recent sample of the Swedish working population. Methods: The study was based on the 2014 data collection of the Swedish Longitudinal Occupational Survey of Health. We assessed the structure of the WTC measure using exploratory and confirmatory factor analysis. Differences in WTC by work and demographic characteristics were examined with independent sample t-tests, one-way ANOVAs and gender-stratified logistic regressions. Results: Best model fit was found for a two-factor structure that distinguished between control over daily hours and control over time off (root mean square error of approximation = 0.06; 95% CI 0.04 to 0.09; Comparative Fit Index (CFI) = 0.99). Women, shift and public-sector workers reported lower control in relation to both factors. Age showed small associations with WTC, while a stronger link was suggested for civil status and family situation. Night, roster and rotating shift work seemed to be the most influential factors on reporting low control over daily hours and time off. Conclusions: Our data confirm the two-dimensional structure underlying WTC, namely the components 'control over daily hours' and 'control over time off'. Women, public-sector and shift workers reported lower levels of control. Future research should examine the public health implications of WTC, in particular whether increased control over daily hours and time off can reduce health problems associated with difficult working-time arrangements.

BACKGROUND: Psychosocial work factors can affect depressive moods, but research is inconclusive if flexibility to self-determine working hours (work-time control, WTC) is associated with depressive symptoms over time. We investigated if either sub-dimension of WTC, control over daily hours and control over time off, was related to depressive symptoms over time and examined causal, reversed-causal, and reciprocal pathways.

METHODS: The study was based on four waves of the Swedish Longitudinal Occupational Survey of Health which is a follow-up of representative samples of the Swedish working population. WTC was measured using a 5-item index. Depressive symptoms were assessed with a brief subscale of the Symptom Checklist. Latent growth curve models and cross-lagged panel models were tested.

RESULTS: Best fit was found for a model with correlated intercepts (control over daily hours) and both correlated intercepts and slopes (control over time off) between WTC and depressive symptoms, with stronger associations for control over time off. Causal models estimating impacts from WTC to subsequent depressive symptoms were best fitting, with a standardised coefficient between -0.023 and -0.048.

LIMITATIONS: Results were mainly based on self-report data and mean age in the study sample was relatively high.

CONCLUSION: Higher WTC was related to fewer depressive symptoms over time albeit small effects. Giving workers control over working hours - especially over taking breaks and vacation - may improve working conditions and buffer against developing depression, potentially by enabling workers to recover more easily and promoting work-life balance.

Objectives Evidence shows that work-time control (WTC) affects health but underlying mechanisms are still unclear. Work-life interference (WLI) might be a step on the causal pathway. The present study examined whether WLI mediates effects on mental and physical health and contrasted these to other causal pathways.

Methods Four biennial waves from the Swedish Longitudinal Occupational Survey of Health (SLOSH, N=26 804) were used. Cross-lagged analyses were conducted to estimate if WLI mediated effects from WTC (differentiating between control over daily hours and time off) to subsequent depressive and musculoskeletal symptoms. Other causal directions (reversed mediation, direct and reversed direct effects) and robustness of mediation (by including covariates) were examined.

Results WLI partially mediated the relationship of WTC (control over daily hours/time off) with both health outcomes. Indirect effect estimates were small for depressive symptoms (-0.053 for control over time off and -0.018 for control over daily hours) and very small for musculoskeletal symptoms (-0.007 and -0.003, respectively). While other causal directions were generally weaker than causal mediational pathways, they played a larger role for musculoskeletal compared to depressive symptoms. Estimates relating to control over time off were in general larger than for control over daily hours.

Conclusions Our results suggest that WLI mediates part of the effect from WTC to mental/musculoskeletal symptoms, but small estimates suggest that (i) WTC plays a small but consistent role in effects on health and (ii) particularly regarding musculoskeletal disorders, other causal directions and mediators need to be further examined.

Aims: Employee-based flexible working hours are increasing, particularly among knowledge workers. Research indicates that women and men use work–time control (WTC; control over time off and daily hours) differently: while men work longer paid hours, women use WTC to counteract work–life interference. In a knowledge-worker sample, we examined associations between WTC and overtime, work–life interference and exhaustion and tested if gender moderates the mediating role of overtime.

Methods: The sample contained 2248 Swedish knowledge workers. Employing hierarchical regression modelling, we examined effects of control over time off/daily hours on subsequent overtime hours, work–life interference and exhaustion in general and in gender-stratified samples. Using conditional process analysis, we tested moderated mediation models.

Results: Control over time off was related to less work–life interference (βmen=-0.117; CI95%: -0.237 to 0.003; βwomen=-0.253; CI95%: -0.386 to -0.120) and lower exhaustion (βmen=-0.199; CI95%: -0.347 to -0.051; βwomen=-0.271; CI95%: -0.443 to -0.100). For control over daily hours, estimates were close to zero. While men worked more overtime (42 minutes/week), we could not confirm gender moderating the indirect effect of control over time off/daily hours on work–life interference/exhaustion via overtime. Independent of gender, effects of control over time off on work–life interference were partly explained by working fewer overtime hours.

Conclusion: Control over time off was related to lower exhaustion and better work–life balance (in particular for women). We found no evidence for men’s work–life interference increasing with higher WTC due to working more overtime. Knowledge workers’ control over time off may aid to prevent work–life interference and burnout.