Rescheduling a three-shift system at a steel rolling mill: effects of a 1-hour delay of shift starting times on sleep and alertness in younger and older workers.
Rosa-RR; Harma-M; Pulli-K; Mulder-M; Nasman-O
Sixth US-Finnish Joint Symposium on Occupational Health and Safety, People and Work, Proceedings of the Sixth FIOH-NIOSH Joint Symposium on Occupational Health and Safety, 8-10 August 1995, Espoo, Finland. People and Work - Research Reports 3. H. Nordman, J. Starck, A. Tossavainen, E. Viikari-Juntura, eds. Helsinki, Finland: Finnish Institute of Occupational Health; 1995 Aug; :173-179
The effects of delaying shift starting times on sleep and alertness in young and older workers were examined. The study group involved workers at a steel rolling mill with a rotating three shift schedule (mill 1) and 140 workers at another mill with a similar shift system except that the shifts began 1 hour later than at mill 1 (mill 2). Four months after being on the new delayed shift system, the workers at mill 1 were surveyed by questionnaire to rate perceived sleep quality, alertness, and fatigue. The results were compared with similar data obtained 6 months before the shift change. A similar survey was performed twice in mill 2. Twenty workers from mill 1 and 25 from mill 2 also kept daily sleep diaries and wore actigraphs on the wrist to record daily rest/activity patterns. Fatigue and alertness during the shifts were measured by a choice reaction time task and a subjective sleepiness scale taken from the NIOSH Fatigue Test Battery. Age effects were evaluated by comparing data obtained for workers older than 40 years with those obtained with younger workers. In mill 1 workers, total sleep time increased and sleep quality improved for morning shift workers and decreased for evening and night shift workers after the shift changes. The differences in sleep time on the morning and night shifts were greater for younger workers than in older workers. Age related effects on sleep quality were not observed. The diary and actigraph data supported the perceived changes in sleep time and quality. The subjective and objective data showed that fatigue and sleepiness during the morning shift was lower in mill 1 workers following the shift changes. Fatigue increased during the evening shift and sleepiness increased during the night shift. No age related effects on fatigue or sleepiness were seen. No significant changes in any of the examined variables were seen in mill 2 workers. The authors conclude that a 1 hour delay in shift starting times improved sleep before the morning shift and decreased sleepiness and fatigue during the morning shift. Age does not have a major interactive effect on these findings.
Shift-work; Steelworkers; Sleep-disorders; Age-factors; Questionnaires; Psychophysiology; Occupational-medicine; Shift-workers; Physiological-fatigue
Nordman-H; Starck-J; Tossavainen-A; Viikari-Juntura-E
Sixth US-Finnish Joint Symposium on Occupational Health and Safety, People and Work, Proceedings of the Sixth FIOH-NIOSH Joint Symposium on Occupational Health and Safety, 8-10 August 1995, Espoo, Finland. People and Work - Research Reports 3