Are Nonstandard Work Schedules Related to Sleep Difficulty and Health-related Quality of Life? An Examination of Gender Differences.

Objectives: The rise of flexible and diverse work schedules has become increasingly common in modern society. This study aims to investigate whether nonstandard work schedules are related to sleep difficulty and other aspects of health-related quality of life (HRQOL) in South Korea, with special attention to gender differences.

Methods: Data from the 2019 and 2021 National Health and Nutrition Examination Survey (Phase 8) were used, with a final sample consisting of 6,735 participants. Ordinal logistic regression analysis was performed on sleep difficulty and the other seven items of the Health-related Quality of Life Instrument with 8 items (HINT-8) to examine associations with work schedules. Linear regression analysis was also conducted using the HINT-8 index as a composite measure.

Results: Nonstandard work schedules were associated with a higher likelihood of sleep disturbances compared to the standard daytime work schedule. In particular, the negative impact of the night work schedule on sleep was greater for female workers than for male workers. Females working under the night work schedule were 12.2 percentage points more likely to report severe sleep difficulty than females under the day work schedule (9.6%). Additionally, the working, happiness, and vitality items of the HINT-8 were negatively associated with the night work schedule, whereas the other HINT-8 items and the HINT-8 index did not exhibit similar results.

Conclusions: Nonstandard work schedules are associated with increased sleep difficulty, particularly among women, and negatively affect several aspects of HRQOL, including vitality, happiness, and work performance. Given their rising prevalence and adverse impact on workers' sleep, health, well-being, as well as workplace safety and performance, nonstandard work schedules should be recognized as a significant public health concern.