We aimed to study the association of perceived control over scheduling of shifts with objectively measured working hour characteristics in shift workers. The participants were 5128 hospital employees (91% women, 85% nursing personnel, average age 43 years) in period-based work (114:45h/3 weeks) from the 2015 Finnish Public Sector study. Survey responses to a measure of control over scheduling of shifts were linked to payroll data on working hour characteristics during the 91 days preceding the survey. We used multinomial logistic regression to assess differences in dichotomized proportion of working hour characteristics (being full-time worker, number of work shifts, long work weeks (>40h and >48h/week), long work shifts (>12-h), evening and night shifts, quick returns (<11h shift interval), single days off, weekend work, >4 consecutive work shifts, and variability of shift length with cut points at 10% or 25% between employees with high, intermediate, or low control over scheduling of shifts. Analyses were adjusted for age, sex, education, full-/part-time work (where applicable), duration of shift work experience, perceived work ability, children < 18 years in the household, and overall stressfulness of the life situation. Differences between age groups, men and women, and levels of work ability were examined using interaction terms. In adjusted analyses, the proportion of full-time workers was lower among employees with intermediate control over scheduling of shifts compared to those with high control (OR 0.78, 95% CI 0.61-0.98). High proportion (>25%) of weekend work was lower among employees with low control over scheduling of shifts compared to high control (OR 0.75, 95% CI 0.61-0.93). High proportion (>25%) of having >4 consecutive work shifts was associated with lower control over scheduling of shifts (OR 1.35, 95% CI 1.13-1.62). Variability of shift length was lower among employees with intermediate and low control over scheduling of shifts compared to those with high control (OR 0.78, 95% CI 0.66-0.93; OR 0.62, 95% CI 0.51-0.75, respectively). No association was observed between the level of control over scheduling of shifts and high proportion of long work weeks (>25% of >40h weeks and >10% of >48h weeks), long work shifts (>25%), quick returns (>25%), single days off (>25%), and evening or night shifts (>10%) in the whole sample. In subgroup analyses, women with low control over scheduling shifts had lower odds ratio (OR 0.58, 95% CI 0.37-0.91) and men had higher odds ratio (OR 2.97, 95% CI 1.26-6.98) for large proportion of >12-h shifts. In conclusion, the employees with high control over scheduling of shifts had slightly more often unsocial working hour characteristics than those with intermediate or low control over scheduling of shifts. The findings, however, suggest that good work time control in shift work can be possible without compromising shift ergonomics.
