In the past years there have been new insights into the effect of the hormone melatonin on the body and I want to share some of this new research findings here.
What is melatonin?
Apart from it's commonly known role in sleep regulation and day/night synchronization, it also seems to have an effect on pain modulation in the central nervous system as well as on inflammatory, immune and cancer protective processes. Melatonin is secreted in the pineal gland in the brain and its primary function is regulation of sleep. New research shows that melatonin is also synthesized in many other regions of the body like skin, gastrointestinal tract and whites blood cells and that it exerts a local hormonal effect on metabolism. Among other functions, extrapineal melatonin has a modulatory role on inflammation, immunity and reducing hyperalgesia, thus contributing to pain control.
What's it's the link to fibromyalgia (FM) and chronic pain?
Melatonin’s effect on pain has been demonstrated in animals for inflammatory and neuropathic pain, as well in acute and chronic pain in humans including fibromyalgia. Previous studies have demonstrated that patients with fibromyalgia have low melatonin secretion (think sleep hormone) with decreased levels of melatonin metabolites in the urine (1). As well, bad sleep quality has been related to the onset of FM and is generally associated with worsening of chronic pain. The observation is that chronic lack of sleep disturbs the brains capability to modulate pain. In other words, lack of sleep can lead to central pain sensitization.
What does research say about fibromyalgia?
Three trials so far have assessed the use of melatonin on fibromyalgia. A recent trial demonstrated that 10 mg melatonin at bedtime produced a large size effect (reduction of daily pain scores by 39.80%) for chronic pelvic pain (2).But study results have not been consistent, possibly because the dosage used has been low (3-5 mg). Hence one trial from 2014 conducted in Brazil assessed the efficacy of 10mg melatonin at bedtime on 63 FM patients, either alone or in combination with amitriptyline compared to amitriptyline alone over 6 weeks (3). The effect was remarkable. Melatonin induced a pain reduction that was higher than 35% in a specific pain test (cold-heat-task). Also a large effect size was observed in the number of tender points and sleep quality. The difference between the group that received melatonin only and the group receiving melatonin + amitriptlyline was minimal which means that melatonin alone may have considerable effects on pain modulation in chronic pain states.
Is it safe?
The side effects of melatonin can include sleepiness and low blood pressure. But because it’s a bioidentical hormone, even high dosages seem to be safe. The use as a supplement depends on age because with age, especially after the 30ies melatonin production declines gradually and with it it's beneficial effects on the body. So a supplementation makes more sense with increasing age and the recommended dosage varies from 1-3 mg in healthy people.
Take Home Message
Emerging evidence demonstrates an analgesic effect of melatonin on chronic pain. Although studies are few, small and the mechanism hasn't been discovered yet, the supplementation with melatonin is safe, cheap and it has many other benefits on the body. Treatment results shouldn't be expected immediately and research shows it takes at least two months to exert an effect that can be noticed. So using the pain diary to get a grasp on the pain levels and your memory might be a good idea!
Also be aware that there is no drug patent to be obtained which makes it uninteresting for the pharmaceutical industry.
Much more could be said about this mysterious hormone but the space here is limited.
Feel free to give feedback, share your own experiences and ask questions.
You can also send them to me if I don't get back after 1-2 days.
Marc Fouradoulas, MD