Melatonin may be more commonly known as the sleep hormone or hormone of darkness.
However, melatonin has many other important biological functions than just regulating sleep-wake cycle.
These biological functions include regulation of immune function, reproductive function, cardiovascular function and memory formation, acting as potent anti-inflammatory and anti-oxidant agent, support of gut health and brain health, protection of detox organs (liver, kidneys), and anti-aging effects.1
Low and dysfunctional melatonin levels can compromise immune function and have been associated with many chronic diseases, not just sleep disorders.
Therefore, it is imperative to maintain healthy melatonin levels.
In my new blog below, I share evidence-based information on the biological and health effects of melatonin and strategies to support healthy melatonin levels.
For a quick summary of the tips to support healthy melatonin levels, you can go directly to the Summary section.
Topic List
Biological and Health Effects of Melatonin
Sleep Hormone: Sleep-Wake Cycle Regulation
Protection of Detox Organs: Liver and Kidneys
Diseases/Disorders Associated with Melatonin Dysfunction and Deficiency
Tips to Support Healthy Melatonin Levels
Align Sleep-Wake-Activity Schedule with the Natural 24-hour Light-Dark Conditions
Consume Natural Food Sources of Melatonin
Adopt Diet and Lifestyle That Reduce Chronic Inflammation
What About Melatonin Supplementation?
Summary
As described in the section Biological and Health Effects of Melatonin, melatonin is much more than just a sleep hormone. It has wide-ranging and important biological functions that should not be overlooked.
Melatonin dysfunction and deficiency can increase the risks of many chronic diseases, including sleep disorders, compromised immune function, heart disease, hypertension, type 2 diabetes, cancer, gut disorders/diseases, brain and neurodegenerative diseases, liver disease, mood disorders, mental illness, chronic pain, obesity, etc. (for more details, see section Diseases/Disorders Associated with Melatonin Dysfunction and Deficiency).
Therefore, it is imperative to support healthy melatonin levels in the body through adequate diet and lifestyle choices as summarized below (for more details, see section Tips to Support Healthy Melatonin Levels).
Melatonin Production
Melatonin is produced by the pineal gland in the brain, where the production is regulated by the natural 24-hour light-dark conditions.1
The pineal gland secretes melatonin when it is dark at night to prepare the body to go to sleep, while the secretion of melatonin is suppressed by daylight.1
In addition to the pineal gland, melatonin is also produced in many other organs and tissues including the gastrointestinal (GI) tract or gut lining, immune cells, skin, bone marrow cells etc. The secretion of melatonin in these tissues are not dependent on light-dark condition.1
The production of melatonin and the presence of melatonin receptors in various organs/tissues reflect the wide-ranging biological functions of melatonin in the body, as discussed below.
In fact, melatonin level found in the gut is 400 times higher than that in the pineal gland.2 The importance of melatonin to gut health is further discussed below.
Biological and Health Effects of Melatonin
Some of the important biological functions of melatonin are discussed below.
Sleep Hormone: Sleep-Wake Cycle Regulation
Melatonin promotes sleep at night and helps to regulate the natural biological clock (called the circadian rhythm) of the body to be in alignment with the natural 24-hour light-dark conditions.1
As melatonin production in the pineal gland is triggered by darkness, exposure to artificial light (e.g. from artificial lightings and device screens), especially blue light, can suppress melatonin production and consequently cause sleep disturbance, and disrupt the natural circadian rhythm.3,4
As discussed in details in my previous article “Tips for Better Sleep to Support Your Immune Health and Overall Health”, disruption of circadian rhythm can have many detrimental health effects, including compromised immune function and increased risks of many chronic diseases (e.g., diabetes, hypertension, heart disease, liver disease, gastrointestinal (GI) disorders/diseases, cancer, Alzheimer’s disease/dementia, and mental illness).
Potent Antioxidant
Melatonin is among the most potent antioxidants in the body.
Antioxidants are important biological compounds in the body that helps to remove excess free radicals or oxidants in the body.
Free radicals or oxidants are produced by normal metabolic processes in the body. Metabolic dysfunction and chronic inflammation can result in excessive free radicals in the body.1
In addition, free radical production is also triggered by external agents including ionizing radiation (e.g. X-rays, radioactive materials), UV light, and environmental toxins.1
When there are excessive free radicals in the body and insufficient antioxidants to counteract, oxidative stress ensues.
Oxidative stress causes cell and tissue damage and is implicated in many chronic diseases including heart disease, high blood pressure, diabetes, cancer, cataract, chronic kidney disease, neurodegenerative diseases (e.g. Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis etc.), and aging.1,5,6
As a potent antioxidant, melatonin acts as direct scavenger of free radicals. Melatonin has 10 times or more free radical scavenging capacity than many other antioxidants.1
In addition, melatonin can act indirectly by stimulating and potentiating the action of other antioxidants in the body.1
Melatonin’s antioxidant properties aid in DNA repair and inhibition of cancer development and growth.1
Melatonin also protects the proper functioning of mitochondria. Mitochondria is the energy-producing machine in a cell. Free radicals are produced in normal energy metabolism. However, mitochondria dysfunction can result in excessive free radicals and oxidative stress in the body.1
Heavy metals (e.g. mercury, lead, arsenic, aluminum, etc.) are environmental toxins that can cause oxidative stress in the body. Melatonin not only acts as an antioxidant but also binds to heavy metals to facilitate their removal from the body, thus reducing metal-induced toxicity and damage to the brain and central nervous system.1
Melatonin dysfunction and deficiency have been associated with many oxidative stress related chronic diseases listed above.1
Immune Regulation
Melatonin modulates various immune functions which helps to maintain a balanced immune system.7
Melatonin stimulates the immune function under certain conditions while suppressing overactive immune processes under other conditions.7
Melatonin enhances immune defense against pathogens (viruses, bacteria, parasites, etc.), in which case melatonin promotes normal inflammatory processes to help to remove pathogens.7
Other the other hand, melatonin exerts potent anti-inflammatory effects under abnormal inflammatory conditions.7
Chronic low-grade inflammation can form a vicious cycle with oxidative stress where one potentiates the other. 1,7
Similar to oxidative stress as previously discussed, chronic low-grade inflammation in the body is also implicated in many chronic diseases and disorders, including heart disease, high blood pressure, diabetes, cancer, neurodegenerative diseases (e.g. Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis etc.), and aging.7
Melatonin dysfunction and deficiency were found to increase the risk of these diseases.7
In animal studies, therapeutic use of melatonin was found to exert neuroprotective effects for Alzheimer’s disease during early phase of the disease.7
Gut Protective Functions
Melatonin plays important roles in gut health:13,14
- Regulate intestinal motility, thus promoting regularity.
- Mediate immune defense against gut pathogens.
- Protect the internal lining (or mucosa barrier) of the gut by preventing permeability and reducing inflammation of the gut lining.
Permeability of the gut lining, also called gut permeability or leaky gut, allows unwanted and harmful compounds (including partially digested food compounds, toxins, pathogens) in the gut lumen to leak into the circulation (i.e., the blood and lymphatic systems).11
Unwanted compounds leaked into the circulation can trigger hyperactive immune response, which in turn results in: 8–12
- Chronic inflammation in the gut, which contributes to inflammatory bowel disease (IBD) and inflammatory bowel syndrome (IBS).
- Chronic low-grade inflammation in the body which has implications on many chronic diseases as previously discussed.
- Food allergies and sensitivities, which may manifest into chronic pain, chronic fatigue, skin issues, etc.
- Autoimmune disorders (e.g. rheumatoid arthritis, multiple sclerosis, celiac disease, systemic lupus erythematosus, etc.).
Gut permeability and chronic inflammation in the gut can also form a vicious cycle.13
There are many contributing factors the gut permeability. Some of these factors include diets low in fiber, high in refined sugars, fructose, saturated fats and processed foods; gluten consumption; toxins in food (e.g. pesticides, herbicides, food additives and chemicals); gut infections; certain drugs, etc.9–12
For a more detailed account on gut health and how gut dysfunction contributes to many other chronic diseases and disorders, please check out my previous article “Why Your Gut Feeling Matters”.
Gut Microbiota Regulation
Melatonin promotes healthy composition of the gut microbiota, an ecological community of microorganisms in the gut.14,17
Sleep deprivation and disruption of circadian rhythm contribute to dysbiosis or imbalance of gut microbiota, i.e. overgrowth of bad or pathogenic microorganisms and undergrowth of good microorganisms.17
Dysbiosis is associated with many chronic diseases/disorders including obesity, type 2 diabetes, high blood pressure, IBS, IBD, nonalcoholic fatty liver disease, colorectal cancer, etc.15,16
In addition, emerging neuroscience research has found the intimate relationship between microbiota, gut and the brain, called the microbiota-gut-brain axis. Dysbiosis and gut permeability have been found to associate with cognitive/psychiatric/neurological disorders such as autism spectrum disorders, anxiety, depression, schizophrenia, and Parkinson’s disease.18–20
Anti-Aging Functions
Oxidative stress and chronic inflammation are implicated in the aging of cells and tissues.21,22
Oxidative stress is also associated with impaired circadian rhythmicity.21,22
Recent scientific studies have shown the roles of melatonin as an anti-aging agent.22–24
Melatonin, as a potent antioxidant and anti-inflammatory agent, helps to combat the long-term accumulative effects of oxidative stress and chronic inflammation in aging process.22–24
Melatonin helps to combat the aging of various organs and tissues in the body and combat many of the previously discussed chronic diseases and disorders often associated with aging.22–24
However, the production of melatonin declines with age, especially in the presence of chronic inflammation.13 Therefore, it is important to adopt a diet and lifestyle that lower chronic inflammation as will be discussed in later section below.
Protection of Detox Organs: Liver and Kidneys
Liver is a major detoxification organ in the body, responsible for neutralizing toxins from chemical pollutants, heavy metals, drugs, alcohol, biotoxins, etc. and promoting excretion of neutralized toxins through the colon.25
Liver injuries and liver diseases ensue when the liver is overloaded with toxins.25
Studies have shown that melatonin could alleviate liver injuries and diseases by preventing oxidative damage, improving mitochondria function, suppressing inflammation and other liver cell alteration processes.25
Toxins not removed by the liver and the colon may end up in the blood circulation and pass through the kidney filtration system to be excreted in the urine.
Kidneys are vulnerable to injuries by toxins, resulting acute kidney injury and chronic kidney disease.26,27
Animal studies have shown that melatonin protects kidneys against acute injuries from heavy metals and chemicals, through its antioxidant actions.28,29
Support of Brain Health
Melatonin was found to exert neuroprotective effects by protecting brain and nerve cells from oxidative damage, cell alteration, and cell death; promoting DNA stability and repair; and promoting new brain/nerve cell generation.1,31,32
As also previously discussed, melatonin can bind to and remove toxic metals from the brain and central nervous system.1,31,32
Melatonin dysfunction and deficiency are associated with neurodegenerative diseases (e.g. Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, etc.) and mental disorders.1,31,32
Melatonin therapy was found to be beneficial for epilepsy management, delaying the progress during early phase of Alzheimer’s disease, alleviating depression-related insomnia, and alleviating migraine and headache.31
Diseases/Disorders Associated with Melatonin Dysfunction and Deficiency
As already discussed, melatonin has such a wide-ranging biological functions and beneficial health effects on various organs and systems in the body.
Melatonin dysfunction and deficiency not only affect sleep but may also increase the risks of many chronic diseases and disorders, as listed below:1,30– 32
- Sleep disorders and disruption of circadian rhythm
- Compromised immune function
- Type 2 diabetes
- Hypertension
- Heart disease
- Liver disease
- GI disorders and diseases
- Cancer
- Brain and neurodegenerative diseases (incl. Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, etc.)
- Mood disorders and mental illness
- Cataracts
- Chronic pain
- Obesity
Tips to Support Healthy Melatonin Levels
Here are some strategies to support healthy production of melatonin in the body.
Align Sleep-Wake-Activity Schedule with the Natural 24-hour Dark-Light Conditions
To support the natural production of melatonin by the pineal gland, it is important to align our daily sleep-wake-activity schedule with the natural 24-hour dark-light conditions.
To avoid exposure to artificial light, especially blue light in the evening and at night, by dimming artificial lighting and minimizing device screen time.
For tips for better sleep and sleep schedule, please check out my previous article “Tips for Better Sleep to Support Your Immune Health and Overall Health”.
Support Gut Health
As previously discussed, melatonin level in the gut is 400 times higher than that in the pineal gland.
Inflammation in the gut can reduce melatonin levels, which in turns reduces melatonin’s protective effects in the gut. A vicious cycle can therefore be formed between gut inflammation and reduced melatonin levels.13
Gut microbiota can influence the biological pathway for the synthesis of melatonin. Therefore, a healthy composition of gut microbiota is also important.13
Melatonin produced in the gut not only supports gut health but may also be released into the blood circulation, thus exerting biological effects in other parts of the body.14
Therefore, it is important to have a healthy gut and gut flora.
Some strategies to promote the health and reduce damage to the gut and gut microbiota include:9–12,33,34
- Avoid or minimize consumption of processed foods, artificial sweeteners, refined carbohydrates.
- Consume a whole food plant rich diet that is high in fibers and prebiotics that feed the good microorganisms.
- Avoid toxins in foods including pesticides, herbicides, heavy metals, food additives, chemicals and environmental pollutants, by choosing organic whole foods whenever possible.
- Avoid consumption of foods that trigger immune reactions and inflammation, i.e. food allergies and sensitivity, which can be highly individualized.
- Consume probiotic-rich foods from a variety of fermented foods or from probiotic supplement.
- Reduce consumption of foods high in saturated fats.
- Choose organic, grass-fed/pasture-raised meat that is free of antibiotics.
- Be aware that certain drugs that can damage gut lining and gut microbiota including antibiotics, NSAIDs, proton pump inhibitors (PPIs), and osmotic laxatives.
For a more detailed account of gut and digestive health, please check out my previous articles: “Why Your Gut Feeling Matters”, and “You are What You Eat? Not Quite”.
Consume Natural Food Sources of Melatonin
Plants are rich sources of melatonin, especially the generative organs of plants, i.e. flowers, fruits, and seeds.35
Some of the plant foods rich in melatonin includes goji berry, strawberry, cherries, pomegranate, turmeric, mustard seed, fenugreek, sunflower seed, flaxseed, corn, cucumber, etc.35
Adopt Diet and Lifestyle That Reduce Chronic inflammation
Chronic inflammation is associated with decreased melatonin levels.13,31
Adopting a diet and lifestyle that is anti-inflammatory not only supports health melatonin levels, but also reduces the risks for many chronic diseases associated with chronic inflammation.
Beneficial dietary composition includes:36–38
- Whole food plant-rich diets consisting of plenty of whole fruits and vegetables of a wide variety of colors, moderate amount of legumes and whole grains, and some nuts and seeds. Such diets are rich in a wide range of antioxidants, fibers and other health promoting micronutrients and phytonutrients, which help to combat oxidative stress, promote anti-inflammatory response, and regulate blood sugar. Leafy greens, cruciferous vegetables, and berries are particularly beneficial.
- Avoidance of refined carbohydrates.
- High ratio of unsaturated fats including monounsaturated fats (e.g. olive, avocado) and omega-3 polyunsaturated fats (e.g. cold-water fish, flaxseed, chia seed, some nuts) over saturated fats.
- Minimum or reduced consumption of foods high in saturated fats and advanced glycation products (AGEs) such as meats (especially red meats and processed meats), foods cooked in high/dry heat, and dairy products especially aged cheese.
- Avoidance of immune reactive foods, i.e., foods that trigger allergies or sensitivities, which can contribute to autoimmunity and inflammation. Food allergies and sensitivities are highly individualized.
Beneficial lifestyle approaches include:
- Healthy weight management through nutrient-dense whole food diets (see above) and adequate physical exercise.
- Minimum exposure to food and environmental toxins by choosing organic foods and toxin-free household and personal care products whenever possible.
- Stress management techniques such as yoga, Tai Chi, meditation, low-intensity exercise, music therapy, etc.
- Adequate sleep.
For more details, please check out my previous article “How to Support Your Immune Health – See What Scientific Research Showed”, which provides a detailed account of diet, lifestyle and chronic inflammation.
What About Melatonin Supplementation?
Therapeutic use of melatonin is more common for sleep disorders, circadian rhythm disorders, jetlag and shift workers.1
Some clinical studies (although some of them are preliminary) have shown the beneficial effects of melatonin therapy in epilepsy management, delaying the progress during early phase of Alzheimer’s disease, alleviating depression-related insomnia, alleviating migraine and headache, alleviating symptoms in IBS, and inhibition of cancer cell growth in colorectal cancer. 14,31
There are, however, some contraindications in melatonin supplementation and caution should be taken.
Melatonin supplementation was found to produce negative effects (i.e., increased inflammation and aggravated symptoms) in autoimmune-related diseases/disorders due to its proinflammatory actions in an already hyperactive immune system. Those autoimmune diseases studied were IBD, rheumatoid arthritis, systemic lupus erythematosus, and multiple sclerosis.7,14
Related Articles
Tips for Better Sleep to Support Your Immune Health and Overall Health
How to Support Your Immune Health – See What Scientific Research Showed
You are What You Eat? Not Quite
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