Shift rotation and age – interactions with sleep–wakefulness and inflammation

The interaction of age with shift rotation in relation to sleep–wakefulness and inflammation were studied among male employees (n = 772). Cross-sectional analyses in day, two-shift and three-shift work with different shift rotations, as well as changes in leukocytes and hsCRP among three shift workers who changed their shift system during the 2.5- yr follow-up were completed. Shift work was associated with problems to fall asleep (p < 0.001) and feeling of the current working time being harmful to sleep and wakefulness (p < 0.001). Quickly forward-rotation shift workers considered their working time less harmful compared with slower backward-rotation shift workers. Age did not influence sleep in general, but older workers in the quickly forward-rotating three-shift system had less sleep complaints than their younger colleagues. The age differences in the inflammatory markers partly depended on the shift system. The results give some support that rapidly forward-rotating shift systems are more ‘age-friendly’ than backward-rotating shift systems.