Study objectives: This study estimated the prevalence, examined associated impacts, and identified correlated factors of poor sleep quality among Japanese white-collar employees who were working in a labor market that included extensive downsizing and restructuring.
Design: A cross-sectional self-administered questionnaire survey was conducted as part of 2 consecutive studies on sleep. Sleep quality was measured with the Pittsburgh Sleep Quality Index.
Setting: A telecommunications company in the Tokyo metropolitan area.
Participants: Of 5,924 workers, 5,090 responded (85.9%). Results from 4,868 daytime employees were analyzed.
Interventions: N/A.
Measurements and results: The 1-month point prevalence of poor sleep quality was approximately 30% to 45% across age and gender and was significantly higher than in the general population of Japanese adults. The overall prevalence of absenteeism, poor physical and psychological health, problems in work performance and personal relationships, and accidents were 16.5%, 18.3%, 17.3%, 2.5%, 2.1%, and 1.8%, respectively. Poor sleepers were more likely to take sick leave, suffer from poor physical and psychological health, and have problems in occupational activities and personal relationships. The most strongly associated factor underlying poor sleep quality was perceived stress, followed by job dissatisfaction, being unmarried, poor bedroom environment, lower academic attainment, younger age, and hypertension.
Conclusions: This study suggests that the cost related to poor sleep quality is extremely high. Comprehensive countermeasures against poor sleep quality at not only the individual, but also the organizational and societal levels, need to be considered for both employees and employers in order that health, safety, and productivity are ensured.