FOLLOW-UP INTERVENTION STUDY ON EFFECTS OF A CHANGE IN SHIFT SCHEDULEON SHIFTWORKERS IN THE CHEMICAL-INDUSTRY

In 1989-1991, our research team accompanied a pilot project concerning changes in shift schedules in an extensive longitudinal study in the chemical industry. The first questionnaire study was carried out under the old shift systems and the second about 7-9 months after the chang e to new shift schedules. In November 1994, 4.5 yr after the change, w e carried out the third questionnaire study in a subgroup of 132 shift workers participating in the pilot project, of which 50 subjects had p articipated in all three surveys. The aim was to investigate the long- term development in the effects of the change in shift systems and in the attitude of the shiftworkers towards the shift system. About 7-9 m onths after the change in shift schedule, improvements were measured b y fatigue, sleep disturbances and in certain aspects of family and soc ial life. It was found that the shiftworkers appreciated the fast shif t relation, and at the end of the pilot phase, 98% of them voted in fa vour of the new shift system. After 4.5 yr, improvements were measured in the attitude of the subjects toward the irregularity of the shift schedule. Impairments were observed regarding neuro-vegetative disturb ances and sleep disturbances on afternoon shift days. The attitude of the subjects toward the backward shift rotation had worsened. These re sults support ergonomic recommendations for the design of shift system s.