Reported Bruxism and Non-restorative Sleep Complaints in Irregular Shift Work

Objectives: All employees of the Finnish Broadcasting Company with irregular shift work (n=750) and an equal number of randomly selected controls in the same company with regular eight-hour daytime work received a standardized questionnaire covering demographic items, employment details, general health experience, physical status, insomnia symptoms, psychosocial status, work satisfaction and performance. Methods: Perceptions of reported bruxism and non-restorative sleep (Diagnostic and Statistical Manual of Mental Disorders-IV and The International Classification of Sleep Disorders Revised) were investigated for the present study. Results: The overall response rate was 58.3 % (53.7 % men). The response rate in the irregular shift work group was 82.3% (56.6 % men) and in the regular daytime work group 34.3 % (46.7 % men). The mean age of males in shift work was 45.0 (SD 10.6) years and of females 42.6 (SD 10.7) years (p<0.001); the corresponding figures for daytime workers were 47.4 (SD 9.7) and 45.5 (SD 10.1) years (NS), respectively. Females were more often than males frequent bruxers (13.2% vs. 8.3%; p<0.05) and reported more often non-restorative sleep (NRS) (41.5% vs. 31.6%; p<0.01), respectively. Irregular shift work was in itself neither associated with bruxism nor NRS, but dissatisfaction with current work shift schedule was significantly associated with both bruxism (p<0.01) and NRS (p<0.001). According to logistic regression, the probability of NRS was significantly positively associated with dissatisfaction with current workshift schedule (p<0.01), frequent bruxism (p<0.05), female gender (p<0.05) and poorer health experience (p<0.05), and significantly negatively associated with age (p<0.05). Conclusions: Self-reported bruxism may signify a sleep problem which, in turn, may exist because of a stressful or otherwise dissatisfying situation in work.