Multiple Sclerosis and Role of Melatonin in Relapse

multiple sclerosis and role of melatonin in relapse

Why symptoms of multiple sclerosis tend to improve in the winter and get worse in the summer has puzzled experts and patients and prompted a number of speculations. Now a team of researchers has offered a new explanation that involves melatonin, which could lead to better treatment opportunities for people with MS.


Over the years, a number of environmental factors have been examined for their role in multiple sclerosis, including how they impact relapse rate. Those environmental elements include exposure to sunlight, presence of Epstein-Barr virus, smoking, vitamin D levels, and upper respiratory infections.

Multiple sclerosis and melatonin study
A group at Brigham and Women’s Hospital, along with colleagues at the Center for Research on Neuroimmunological Diseases in Argentina, have identified a hormone, melatonin, as playing a part in the activity of multiple sclerosis. Melatonin is perhaps best known as the hormone that helps regulate a person’s sleep-wake cycle.

The team uncovered this relationship while they were exploring the association between environmental factors and the phenomenon in which individuals with multiple sclerosis tend to improve in autumn and winter months but worsen in spring and summer. The study group included 139 patients with relapsing-remitting multiple sclerosis.

First, the researcher noted that the participants experienced a significant improvement in their symptoms during fall and winter. They then evaluated various environmental factors and determined that melatonin level was the one factor that was consistently associated with MS symptom severity.


Levels of melatonin change with the seasons: they are lower during spring and summer and higher during the fall and winter months. The team then utilized a mouse model and human cells to determine the effects of melatonin on cells that are involved in the immune response that leads to multiple sclerosis.

Here’s what the researchers found:

  • Melatonin had an impact on the roles of cells that play a key role in the progression of MS: pathogenic (aka effector) T cells, which destroy tissues; and regulatory T cells, which act as guards to keep the activities of pathogenic T cells in line.
  • Melatonin helped prevent the pathogenic T cells from causing too much damage in individuals with MS
  • Therefore, the authors concluded that seasonal changes in levels of melatonin may contribute to the reduced disease activity seen in fall and winter months and that this impact may be explained at least in part by the activity of pathogenic and regulatory T cells. This makes sense since the balance between these two categories of T cells controls activity of multiple sclerosis.

However, the authors were quick to point out that people with multiple sclerosis should not start taking melatonin. According to the study’s leader, Francisco Quintana, PhD, it’s too soon to recommend this hormone, which is available over the counter and frequently taken to help manage insomnia.

Quintana noted that “In the future, melatonin or its derivatives may be used in MS patients,” but not until further research has been done. For now, “our data do not show that melatonin or its analogs are effective in treating MS.” Perhaps the pilot clinical trial now being planned will contribute data toward that determination.

As an aside, this study makes me wonder about people with multiple sclerosis who may be taking melatonin for insomnia or other reasons. It would be interesting to know if taking the hormone has had any impact on their relapse rates.

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Farez MF et al. Melatonin contributes to the seasonality of multiple sclerosis relapses. Cell 2015; 162(6): 1338


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