Association of job strain with working hours, shift-dependent perceived workload, sleepiness and recovery

We explored the relationship of job strain with working hours, shift-dependent perceived workload, sleepiness and recovery. Nurses/nursing assistants (n=95) were recruited from wards that belonged to either the top (high-strain group, HJS) or the bottom (low-strain group, LJS) job strain quartiles of a Job Content Questionnaire survey of employees in five health care districts and four cities in Finland. Three-week field measurements during naturally occurring shift schedules and a subset of pre-selected shift arrangements consisted of the Karolinska Sleepiness Scale, perceived workload and recovery. The HJS group (n=42) had more single days off and quick returns than the LJS group (n=53, p<0.01), and both mental workload and physical workload were rated as higher (p<0.01). During naturally occurring shift arrangements, severe sleepiness was more common in the HJS group only in quick returns (p=0.04) and the HJS group recovered on average more poorly from work after all shifts (p=0.01) and morning shifts (p=0.02). During pre-selected shift arrangements, the differences between the groups were only minor. In conclusion, job strain-related differences in sleepiness and recovery were mostly attributable to differences in shift arrangements. Practitioner Summary: High job strain among shift workers is associated with higher perceived work load, poorer ergonomics in work schedules and low control over shift scheduling. Ergonomics in shift planning and better opportunities to influence working hours and workload should be implemented to reduce work strain.