Melatonin: Good for More Than Just Sleep
By Andrea Vannelli,
Melatonin is a light-sensitive hormone that is found in nearly all animals, as well as in many plants where it typically functions as a growth factor. Most people know it as a sleep hormone, but melatonin also plays a major antioxidant role, helping organisms respond to environmental stressors. It also helps regulate body temperature, blood pressure, cell proliferation, immune system activity, and protects neurons. Melatonin is therefore widespread throughout the body and is particularly abundant in the nervous and immune systems. Low melatonin is associated with sleep disturbances, aging, dementia, chronic pain, insulin resistance and some mood disorders.
Melatonin contributes to the rhythmicity of our sleep-wake cycles by opposing cortisol. As cortisol rises and peaks during the daytime, melatonin secretion is triggered by the natural decrease in light that comes with the setting sun. There are photo-receptive cells in the retina that tell the pineal gland and regulate its release of melatonin. Key signaling times of the day are when the light is in transition, just before dawn and dusk, because they provide information to help the body know which direction to go in terms of rest and alertness. Getting naked-eye exposure to the outdoors in the very early part of the day and at twilight can help regulate melatonin cycles. This is much more effective and powerful if exposure to bright or blue light is also limited in the evening hours before bed, because light pollution functions as a massive endocrine disruptor that suppresses the body’s release of melatonin.
Melatonin helps the brain to clean itself by enhancing the activity of several detox pathways. It can also increase glutathione levels, which is the body’s master antioxidant. Outside the brain, melatonin concentrations hundreds of times higher are found in the gut, where it plays a role in stabilizing histamine intolerance, modulating immunity and calming inflammation. Studies have shown that melatonin’s anti-inflammatory and antioxidant properties can improve gut motility and help reduce symptoms associated with IBS. Additionally, it has an overall positive effect on the microbiome.
Melatonin also can help reproductive functions in both men and women. Supplementing high doses has been shown to regulate the menstrual cycle, reduce pain and inflammation associated with endometriosis, and boost egg quality in women by preventing mitochondrial damage. In men, it’s been shown to improve sperm quality and quantity.
Because melatonin is present in plants, it’s found naturally in common foods. Many of these foods include cofactors such as vitamin B6 and tryptophan, which help to promote serotonin and produce a sleepy effect. Some foods high in melatonin include:
- Fruit: tart cherries, goji berries, bananas, grapes
- Nuts: pistachios, almonds
- Beans: most varieties
- Fatty fish: salmon, mackerel, sardines
- Grains: rice, whole oats, corn
- Mushrooms: all types
- Milk
Melatonin supplementation is generally considered safe for short-term use as it doesn’t create dependence, however, it’s always advisable to support your own body’s production of melatonin first. For most people, proper nourishment and regulation are enough to naturally support adequate levels of endogenous melatonin. Supplementation helps modulate the body’s internal clock and can help with falling asleep faster, but not necessarily with staying asleep longer. For this reason, melatonin supplements can be quite useful for facilitating a shift in sleep-wake rhythm, such as adjusting to a new time zone or switching between day and night work shifts.
Be sure to start with a quality supplement that can provide consistent dosages, and be mindful of overdoing it. Starting with the smallest possible dose is advisable (1-3mg is commonly effective), slowly increasing in small increments as needed. Over-use, over-dosing, or improper timing can result in side effects such as daytime drowsiness, headaches or nausea. Melatonin may also lead to more vivid dreams because it increases time in REM sleep.
Melatonin production is highest in our younger years, peaking in early childhood, so supplementing melatonin is not necessary or suitable for children. Typically adjustments to routine or environment are most effective for sleep problems there. It’s also best to avoid supplementing in cases of pregnancy/breastfeeding, or those with depression, seizure or auto-immune disorders.
Iesanu, M. I., Zahiu, C. D. M., Dogaru, I.-A., Chitimus, D. M., Pircalabioru, G. G., Voiculescu, S. E., Isac, S., Galos, F., Pavel, B., O’Mahony, S. M., Zagrean, A.-M. (2022). Melatonin–Microbiome Two-Sided Interaction in Dysbiosis-Associated Conditions. Antioxidants, 11(11), 2244.
https://doi.org/10.3390/antiox11112244.
Kvetnoy, I., Ivanov, D., Mironova, E., Evsyukova, I., Nasyrov, R., Kvetnaia, T., & Polyakova, V. (2022). Melatonin as the Cornerstone of Neuroimmunoendocrinology. International journal of molecular sciences, 23(3), 1835. https://doi.org/10.3390/ijms23031835
Phillips, A. J. K., Vidafar, P., Burns, A. C., McGlashan, E. M., Anderson, C., Rajaratnam, S. M. W., Lockley, S. W., & Cain, S. W. (2019). High sensitivity and interindividual variability in the response of the human circadian system to evening light. Proceedings of the National Academy of Sciences of the United States of America, 116(24), 12019–12024. https://doi.org/10.1073/pnas.1901824116
Takasaki, A., Nakamura, Y., Tamura, H., Shimamura, K., & Morioka, H. (2004). Melatonin as a new drug for improving oocyte quality. Reproductive medicine and biology, 2(4), 139–144. https://doi.org/10.1111/j.1447-0578.2003.00035.x
Tordjman, S., Chokron, S., Delorme, R., Charrier, A., Bellissant, E., Jaafari, N., & Fougerou, C. (2017). Melatonin: Pharmacology, Functions and Therapeutic Benefits. Current neuropharmacology, 15(3), 434–443. https://doi.org/10.2174/1570159X14666161228122115
