Previous research has determined that shift work—working during the night or rotating working hours—increases the risk of cardiovascular disease, thyroid disorders, and cancer. Circadian disruption and sleep restriction are associated with working night shifts; these factors are believed to disturb melatonin secretion and increase inflammatory responses, promoting disease states. Multiple sclerosis is a central nervous system autoimmune inflammatory disorder that has an important environmental component, thus investigating lifestyle risk factors, such as sleep loss related to shift work, is an important objective and the focus of the current study.
The researchers analyzed data from two population-based studies—one with 1343 incident cases of multiple sclerosis and 2900 controls and another with 5129 prevalent multiple sclerosis cases and 4509 controls. The team compared the occurrence of multiple sclerosis among study subjects exposed to shift work at various ages against those who had never been exposed. All study subjects resided in Sweden and were between the ages of 16 and 70. Shift work was defined as permanent or alternating working hours between 9 p.m. and 7 a.m.
“Our analysis revealed a significant association between working shift at a young age and occurrence of multiple sclerosis,” explains researcher Dr. Hedström. “Given the association was observed in two independent studies strongly supports a true relationship between shift work and multiple sclerosis risk.” Results showed that those in the incident multiple sclerosis cohort who had worked off-hour shifts for three years or longer before age 20 had double the multiple sclerosis risk compared with those who never worked shifts. Similarly, subjects in the prevalent cohort who engaged in shift work as teens had slightly more than double the multiple sclerosis risk than subjects who never worked shifts.
The authors suggest that disruption of circadian rhythm and sleep loss may play a role in the development of multiple sclerosis; however the exact mechanisms behind this increased multiple sclerosis risk remain unclear and further study is needed.
Reference for: Association Between Shift Work And Increased Multiple Sclerosis Risk
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