JMIR Publications

ABSTRACT

Background:

Long working hours are a risk factor for short sleep duration among workers, suggesting that high stress under long working hours is associated with sleep. Sense of coherence (SOC) is a dispositional orientation that allows individuals to be more resilient to stressors in daily life. High SOC can maintain sleep under long working hours.

Objective:

This study aimed to investigate the interaction between SOC and long working hours on total sleep time among Japanese workers. We hypothesized that individuals with higher SOC would be less susceptible to sleep reduction associated with long working hours compared to those with lower SOC.

Methods:

A questionnaire and an actigraphy-based cross-sectional survey were conducted among workers in Ibaraki and Tokyo prefectures in Japan. The 13-item SOC scale was used to obtain responses, and weekly working hours were recorded. Total sleep time (TST) per day was measured with an actigraphy device worn for 1 week. Long working hours were defined as more than 50 hours per week; multiple regression analysis with TST as the dependent variable was performed to examine the interaction between long working hours and SOC. A simple slope analysis was performed for further analysis of the interaction.

Results:

A total of 785 workers from 540 surveyed workers were included in the analysis. Multiple regression analysis showed a decrease in TST for long working hours alone, whilst an interaction between long working hours and SOC was associated with an increase in TST. Single slope analysis showed that lower SOC was associated with a greater decrease in TST.

Conclusions:

Our findings suggest the need for interventions designed to promote SOC in protecting the sleep of workers during long working hours.