MS Changes With the Seasons

Multiple sclerosis (MS), for most people, has an unpredictable way it changes over time. While MS is generally progressive, meaning it gets worse with time, there are periods of remission and periods of relapse. Naturally, things that make a relapse more likely are worth avoiding and anything that keeps disease progression at bay is worth seeking out.

Scientists have noticed for some time that relapses are more likely at different times of year. There’s a seasonality to this disease. When large groups of MS patients are tracked over time, it becomes clear that this disease is more active in the spring and summer months. Some of this disease variation is accounted for by weather since higher body temperatures interfere with nerve conduction along demyelinated nerve pathways. In fact, in the early days of understanding and treating MS, a “hot bath test” was actually used in the diagnostic process. If someone suspected of having MS experienced neurologic symptoms (or a worsening of symptoms) after sitting in a hot bath, then MS was diagnosed.

As scientists continue to explore the variables that influence this disease, a new connection has been suggested: melatonin. Melatonin is a hormone made in the brain; it’s often called the sleep hormone since it regulates the body’s internal clock. People tend to have higher levels of melatonin in the fall and winter, which correlate with the times of year of fewer disease flares. Research in animals found melatonin to lessen MS symptoms. Meanwhile, research in humans is just starting. One study of 139 MS patients observed that when melatonin levels were lower, the risk of relapse was higher. For this group, there was a 32% lower chance of relapse in the fall and winter months (the times of naturally high melatonin levels).

It is important to note that the research with melatonin and MS remains in the early stages. More research remains to be done, in order to clarify the relationship of melatonin to MS, as well as the potential value of supplementing with this hormone.

Stephen C. Vogt, Pharm.D.
President and CEO
BioPlus Specialty Pharmacy


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Farez MF, Mascanfroni ID, Medez-Huergo SP, et al. Melatonin contributes to the seasonality of multiple sclerosis relapses. Cell 2015;162(6):1338-52.

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