15 Causes And Risk Factors Linked To Multiple Sclerosis

11. Shift Work and Disrupted Sleep Cycles

Circadian rhythm disruptions—common in night-shift workers and frequent travelers—may influence MS risk by interfering with immune regulation and hormone production. Melatonin, which helps modulate immune function, is suppressed by artificial light at night. Irregular sleep cycles also increase systemic inflammation and stress hormone levels, both of which have been implicated in autoimmune responses. While the link is still being studied, several large-scale investigations have shown that people with long-term shift work history, especially women, have a higher incidence of MS. Protecting your sleep may not just safeguard your mental health—it could help protect your nervous system, too.

12. Epstein-Barr Virus (EBV) Reactivation

While EBV infection is nearly universal, its reactivation in adulthood may play a pivotal role in triggering MS. Studies show that individuals who developed mononucleosis (a common EBV illness) during adolescence are significantly more likely to later be diagnosed with MS. The theory is that EBV may alter B-cell function in a way that primes the immune system for a future attack on myelin—the protective sheath around nerves. One landmark study found that virtually all MS patients had prior EBV exposure. While the virus alone isn’t enough to cause MS, it’s now considered one of the strongest known risk factors.