Swedish researchers have discovered a link between shift work and increased risk of multiple sclerosis (MS). The results of their unique study can be read in the Annals of Neurology, a publication of Wiley-Blackwell on behalf of the American Neurological Association and Child Neurology Society. The study shows that young people below the age of 20 years employed in off-hour jobs could potentially be at risk of developing MS because of disruptions in their circadian rhythm and sleep-pattern.
Earlier studies established that off-hour work employment, whether it consists of working night shifts or rotating working hours, increases the risk of thyroid disorders, cardiovascular disease and cancer. Night shifts are linked to sleep restriction and circadian disruption, which researchers believe is due to the disruption of secreting melatonin and higher inflammatory responses that result in promoting disease.
Scientists decided to focus their investigation on whether MS, a central nervous system autoimmune inflammatory disorder with significant environmental components could be a lifestyle risk factor that is associated with sleep loss due to shift work.
Dr. Anna Karin Hedström and her team from the Karolinska Institutet in Stockholm evaluated data from two population-based studies amongst Swedish residents between the ages of 16 to 70 years. The first study consisted of 1,343 MS cases with 2,900 controls, whilst the other study involved 5,129 prevalent MS cases and 4,509 controls. The definition of shirt work was either permanent or alternate working hours between 9 p.m. and 7 a.m. The researchers compared MS occurrence amongst participants of different ages who worked shift work compared with those who worked during daytime hours.
Dr. Hedström commented:
"Our analysis revealed a significant association between working shift at a young age and occurrence of MS. Given the association was observed in two independent studies strongly supports a true relationship between shift work and disease risk."
Their study findings revealed that participants within the incident MS cohort working three years or more in off-hour shifts before their 20th birthday were twice as much at risk of developing MS compared with those who worked daytime jobs, similar results were observed in the prevalent cohort. Those who worked shifts in their teens had a two-times slightly higher risk of developing MS compared with those who never worked shifts.
According to the authors disruption of circadian rhythm and sleep loss may be associated with the development of MS, but because the precise mechanism for the increased risk remains unclear, further studies are necessary in order to determine the precise process that leads to the increased risk.
Written by Petra Rattue