Shift Work May Reduce Cognitive Performance

Dr. Philip Tucker Department of Psychology | Yr Adran Seicoleg College of Human and Health Sciences | Coleg y Gwyddorau Dynol ac lechyd Swansea University | Prifysgol Abertawe Singleton Park | Parc Singleton Swansea | Abertawe  Medical Research: What is the background for this Interview with:
Dr. Philip Tucker
Department of Psychology | Yr Adran Seicoleg
College of Human and Health Sciences | Coleg y Gwyddorau Dynol ac lechyd
Swansea University | Prifysgol Abertawe
Singleton Park | Parc Singleton Swansea | Abertawe

Medical Research: What is the background for this study? What are the main findings?

Dr. Tucker: Shift work, like jet-lag, is known to disrupt workers’ normal circadian rhythms (i.e. their body clocks) and their social life. It is also associated with greater risk of developing ulcers, cardiovascular disease, metabolic syndrome, breast cancer and reproductive problems. Several studies have also shown that shift workers experience heightened fatigue and sleepiness, particularly at night, and this may affect job performance and safety. However, very little is known about the long-term consequences of shift work on cognitive abilities. We followed a large sample of shift workers and non-shift workers over 10 years, testing their cognitive performance every 5 years. We found that the shift workers’ cognitive performance was lower than that of the day workers.  The difference was greatest for those who had worked shifts for more than 10 years. The shift workers’ cognitive function recovered after they quit shift work, but this recovery took at least 5 years from time that they stopped working shifts. The effects could not be attributed to poorer sleep quality among shift workers. Rather, it seems likely that the findings reflect the disruption of the shift workers’ circadian rhythms, which as been shown by other researchers to have an impact on brain structures involved in cognition and mental health over the lifespan.

Medical Research: What should clinicians and patients take away from your report?

Dr. Tucker: The cognitive impairment associated with shift work may have consequences for the safety of shift workers and the society that they serve, as well as for shift workers’ quality of life.  The findings highlight the importance of maintaining medical surveillance of shift workers, especially of those who have remained in shift work for 10 years or more. They also highlight the potential benefits of arranging shift patterns in ways that minimize circadian disruption.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Tucker: Further research is needed to identify the relative impact of different types of shift patterns on cognitive impairment. It is also important to investigate the possible roles of certain medical conditions (e.g. metabolic disorders and vitamin D deficiency) in the relationship between shift work and impaired cognition.



Chronic Effects of Shift Work on Cognition: findings from the VISAT longitudinal study

 Jean-Claude Marquié, Philip Tucker, Simon Folkard, Catherine GentilDavid Ansiau

Occup Environ Med oemed-2013-101993Published Online First: 3 November 2014doi:10.1136/oemed-2013-101993


Last Updated on October 24, 2015 by Marie Benz MD FAAD