Age and work environment characteristics in relation to sleep: Additive, interactive and curvilinear effects.

Although additive combinations of age and work environment characteristics have been found to predict sleep impairment, possible age x work environment interactions have been largely disregarded. The present study examined linear and curvilinear interactions of age with work environment measures in relation to sleep quality and duration. Survey data were collected from offshore day-shift personnel (N = 901). Main effects and interactions of the age terms with work environment measures (job demand, control, and social support, physical environment and strenuous work) were evaluated. Sleep duration was predicted by a curvilinear interaction, age(2) x job demand (p < .005), and by the age x social support interaction (p < .002); sleep quality was predicted by age x job demand (p < .002). Job control and physical environment showed significant additive effects. At a time when older employees are encouraged to remain in the workforce, the findings serve to increase understanding of how ageing and work demands jointly contribute to sleep impairment.