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UNITED STATES DEPARTMENT OF LABOR

Sustaining sleep: Results from the randomized controlled Work, Family, and Health Study (Crain et al., 2019)

Review Guidelines

Causal Evidence Guidelines

Absence of conflict of interest

Citation

Crain, T. L., Hammer, L. B., Bodner, T., Olson, R., Kossek, E. E., Moen, P., & Buxton, O. M. (2019). Sustaining sleep: Results from the randomized controlled Work, Family, and Health Study. Journal of Occupational Health Psychology, 24(1), 180–197.

Highlights

  • The study’s objective was to examine the impact of a work-family intervention targeting employee control over work schedule and family-supportive supervisor behaviors on employees’ sleep quantity and quality and attitudes about work.  

  • The study was a randomized controlled trial that compared outcomes of treatment and control group members 6, 12, and 18 months after the intervention. Data was collected through face-to-face interviews and through sleep monitors worn by participants. 

  • The study reported that treatment group participants logged more sleep time and experienced less sleep insufficiency than control group participants. The study suggested that the treatment was associated with total sleep time and several sleep-related attitudes. 

  • The quality of causal evidence presented in this study is low because the authors do not provide sufficient information to determine attrition from the study nor whether the groups were similar before the intervention. This means we could not be confident that any estimated effects would be attributable to the work-family intervention and not to other factors.  

Intervention Examined

Work, Family, & Health Study (WFHS)

Features of the Intervention

The Work, Family, & Health Study (WFHS) built on a growing literature examining associations among work-family experiences and sleep outcomes by testing a work-family intervention in two different industries. The intervention had two main aspects: (1) training sessions for supervisors and employees aimed at increasing employees’ control over their work schedules and (2) training and behavior tracking for supervisors aimed at increasing their support for employees’ family and non-work lives. This report focused on one of the WFHS industries, information technology (IT), studying non-contract workers at a large Fortune 500 IT company located in one of two cities. 

Features of the Study

The study was a randomized controlled trial. The authors identified 56 work groups, comprised of individuals who reported to the same manager or worked collaboratively on common projects. Work groups were sorted based on a few categories, such as number of employees at each location, and then an adaptative random assignment approach was used to assign groups to either the intervention or comparison condition. While 56 work groups were randomly assigned, the authors do not report the number of individuals included. The treatment condition was assignment to the intervention, while the comparison condition was assignment to business-as-usual. 

Data was collected at four timepoints: baseline and then six, 12, and 18 months after the intervention. At each timepoint, 60-minute interviews were conducted by trained interviewers at the workplace on company time. Following each interview, participants were asked to wear a sleep monitor on their non-dominant wrist at all times for the next week. The authors report that the final analytic sample was 791 individuals, but do not report how many individuals were in each condition. The sample of individuals with valid sleep monitor data declined over time, from 618 at baseline to 397 at the 18-month follow-up. 

The authors used a statistical model to compare the outcomes of treatment and control group members over time. The model nested timepoints within participants and participants within work groups to examine the impact of the treatment at each timepoint. 

Findings

Health and Safety

  • The study finds that treatment group participants logged more sleep time and experienced less sleep insufficiency than control group participants. However, there was no effect of treatment on insomnia or wake after sleep onset. Moreover, the treatment effect was sustained after 18 months.  

Attitudes

  • The intervention was positively related to total sleep time and indirectly positively related to perceived control over work schedule. Perceptions of greater control over work were negatively associated with sleep insufficiency and perceived work to family conflict. It was indirectly and positively related to family time adequacy. Improved perceptions of family time adequacy were indirectly and positively associated with total sleep time.  

Considerations for Interpreting the Findings

The authors did not provide sufficient information to determine attrition and did not respond to a query seeking this information. Therefore, CLEAR must assume that the study does not meet requirements for low attrition. The authors also did not provide sufficient information to determine whether the intervention and comparison groups used in the analysis were sufficiently similar at baseline, nor did the analytic models appear to account for sufficient pre-intervention characteristics. Therefore, CLEAR must assume that preexisting differences between the groups could potentially explain any observed differences in outcomes. 

Causal Evidence Rating

The quality of causal evidence presented in this study is low because the authors do not provide sufficient information to determine whether attrition from the study was low or the groups being compared were similar before the intervention. This means we could not be confident that any estimated effects would be attributable to the work-family intervention and not to other factors. 

Reviewed by CLEAR

May 2022