Association of annual household income and insomnia symptoms based on work-life balance among Japanese female workers in older adult care services: A cross-sectional study.

PURPOSE: Socioeconomic status has been associated with sleep disturbance; however, the link between annual household income and insomnia symptoms, considering the additive association with work-life balance, has yet to be examined. Therefore, we investigated this association among Japanese female care workers.

METHODS

Between 2015 and 2016, 451 women aged 18-60 years who worked in older adult care services were enrolled in this cross-sectional study. Insomnia symptoms were measured using the Athens Insomnia Scale. Categorized annual household income was divided into two categories (high/middle vs. low) based on the median annual household income from the national survey. Work-life balance was assessed by examining work-to-family and family-to-work conflicts. Exposure was defined as a combined category of income and work-life balance. Data were collected via self-administered questionnaires. Prevalence ratios (PRs) of insomnia symptoms were estimated using modified Poisson regression.

RESULTS

The multivariable-adjusted PR (95% confidence interval [CI]) of insomnia symptoms was 1.43 (1.01-2.01) in the low- compared with the high/middle-income group. Compared with the group with high/middle income and better work-life balance, the PR (95% CI) of insomnia symptoms was 1.27 (0.80-2.00) among those with low income and better work-life balance. Meanwhile, high PRs were observed for both income groups with a worse work-life balance (2.00 [1.45-2.74] for high/middle income and 3.02 [2.00-4.56] for low income).

CONCLUSIONS

Improving work-life balance may help mitigate insomnia symptoms regardless of income, while low income was associated with a higher prevalence of insomnia symptoms.