Melatonin May be Linked to Multiple Sclerosis Symptoms

The mystery of why multiple sclerosis (MS) symptoms get better in the winter and worse in the summer may be solved as scientists found that melatonin could influence MS disease activity. Melatonin is a hormone involved in regulating a person’s sleep-wake cycle.

Researchers warn that this should not inspire patients to discontinue current medications or begin taking melatonin. Rather, investigators hope this discovery will influence better and more targeted therapies.

“We know that for multiple sclerosis and most autoimmune disease, both genetic and environmental factors play an important role, but in the last decade or so, most research has focused only on the genetic side of the equation,” said co-corresponding author Francisco Quintana, PhD, associate professor in the Ann Romney Center for Neurologic Diseases at BWH. “But we wanted to see what environmental factors would reveal to us about this disease. We knew that MS disease activity changed with the seasons. What we’ve uncovered offers an explanation for why that is the case.”

The research team found that during the fall and winter months, a group of 139 relapsing remitting MS patients experienced a significant improvement in symptoms. The team then explored a variety of environmental factors that have been proposed as possible links to MS symptoms, including vitamin D levels, UV incidence, and upper respiratory tract infections.

The one factor that remained consistent among MS symptoms was melatonin. Melatonin levels correlate to day length, with levels being lower in the spring and summer months, while levels remain high in fall and winter months.

The researchers continued to observe the role that melatonin may play at a cellular level. They tested the effects of melatonin on certain types of cells in both human cells and mouse models which were known to play a role in the immune response that leads to MS symptoms.

The team found that melatonin affected the roles of 2 kind of cells that are important in MS disease progression: pathogenic T cells that directly attack and destroy tissue and regulatory T cells that are supposed to keep pathogenic T cells in check.

“We found that melatonin has a protective effect,” Dr. Quintana said. “It dampens the immune response and helps keep the bad guys — or pathogenic T cells – at bay.”

While melatonin is available over the counter, the drug has unwanted side effects including drowsiness. The goal is to discover the exact role of melatonin in order to develop safer, targeted drugs that have minimal side effects.

The team plans to hold a clinical trial to further evaluate the safety and efficacy of melatonin signal targeting in MS patients.

“In the future, melatonin or its derivatives may be used in MS patients after appropriate clinical trials are conducted and dosage is established,” Dr. Quintana said. “However, extreme caution should be exercised: our data do not show that melatonin or its analogs are effective in treating MS.”