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Melatonin and vitamin D – the 24-hour rescue team

Melatonin and vitamin D – the 24-hour rescue teamIn the summertime, we synthesize vitamin D in our skin when we expose ourselves to sunlight. Vitamin D is a nutrient that is of vital importance to mood and health in general. When it is dark outside, we produce melatonin, which is important for our sleep. In addition to that, melatonin has a number of other important functions. Over the past decades, science has focused on its potential in the prevention of cancer, Alzheimer’s disease, sclerosis, and several other diseases. Apparently, vitamin D and melatonin work as hormones day and night and are of vital importance to the immune system. Also, they regulate inflammation, protect cells, and have many other functions. In a new review article that is published in Nutrients, the scientists refer to melatonin as the “next vitamin D”. Also, they mention that many people get too little sunlight during the day and too little darkness at night, which results in a deficiency of both vitamin D and melatonin.

In their review article, the scientists mention that vitamin D and melatonin react to light and darkness, respectively, and that both substances have vital functions in the body that include:

  • Hormonal activity
  • Antioxidant properties
  • Antiinflammatory properties
  • Regulation of the immune defense
  • Regulation of the mitochondria – the energy-producing powerhouses inside the cells
  • More comprehensive systemic effects

Both vitamin D and melatonin are important for all cells in the body. The pineal gland synthesizes melatonin from the amino acid tryptophan when it gets dark outside. Interestingly, we produce 400 times more melatonin in our intestinal mucosa, and melatonin synthesis hinges on the nutrients in our food. Melatonin has also been found in numerous other tissues and body fluids.
Our endogenous melatonin synthesis peaks in our early childhood years and gradually decreases from that point onward. Older people only produce limited quantities, which is partly due to the fact that the pineal gland calcifies over time. Many women are exposed to a substantial drop in melatonin after menopause and that can explain why they have problems with their sleep.
The ageing process reduces our melatonin synthesis, but it is also affected by disease, lack of nutrients, caffeine, medicine, and stress. The major cause of a disrupted melatonin synthesis, however, is jet lag, nightshift work, and overexposure to blue light from the screens of electronic devices like smartphones, computers, TVs, and LED light (light-emitting diode), which can affect all age groups.

The synergistic effect between vitamin D and melatonin

Vitamin D and melatonin appear to complement one another in numerous ways. For example, melatonin can bind to and regulate different proteins, enzymes, and receptors. Melatonin is even able to bind to vitamin D receptors and help vitamin D in its signaling of gene activities. There is also an interplay between vitamin D and melatonin in the skin. When we produce vitamin D in response to UVB exposure from the sun, melatonin serves as a powerful antioxidant and protects the skin.

Melatonin’s role as an antioxidant, a sleep agent, and other things

Melatonin is a powerful antioxidant and protects tissues and organs against oxidative stress caused by free radicals. We generate free radicals as a natural byproduct of our energy turnover and other metabolic processes. Cascades of free radicals are also generated by the ageing process, chronic inflammation, poisoning, smoking, type 2 diabetes, and chronic diseases. Oxidative stress is an imbalance between harmful free radicals and protective antioxidants where free radicals outnumber the antioxidants, thereby damaging cells and tissues. Melatonin is very important in this connection, especially during our sleep where melatonin repairs damaged cells. The above-mentioned review article looks at melatonin with relation to the following:

  • Mitochondria
    The energy turnover takes place inside the mitochondria, which means they are vulnerable to oxidative stress. The mitochondria store a lot of melatonin in their membranes for protection. It is assumed that melatonin supplementation can delay the ageing process, which is associated with impaired mitochondrial function.
  • The 24-hour rhythm (circadian rhythm)
    It is natural for us to be awake during the day and to sleep at night. Melatonin contributes to the deep sleep that is of vital importance to our dream activity, and it detoxifies the brain by clearing out toxic metabolites.
  • Sleep disturbances
    Teenagers often have a displaced day-and-night rhythm. Other things that an disturb our natural day-and-night rhythm include the ageing process, hormone disruptions (including menopause), jet lag, nightshift work, energy drinks, unstable blood sugar, various diseases, and blindness where we are unable to register light and darkness. If the regular advice about diet, alcohol, exercise, and less exposure to light at night fails to work, a melatonin supplement is worth trying.
  • Jet lag
    People travel more than they used to, which is why more and more people suffer from jet lag. This can have a negative effect on your sleep, digestion, and other functions. A large Cochrane review shows that melatonin supplements can effectively reduce jet lag, especially if you are traveling eastbound across five time zones.
  • The central nervous system, depression, and cogntive functions
    We produce melatonin in our pineal gland, and melatonin from the blood can cross the blood-brain barrier and improve the antioxidant protection of the central nervous system. Lack of sleep and too little melatonin are known to increase the risk of depression, Alzheimer’s disease, and other neurodegenerative disorders because of oxidative stress, inflammatory processes, and toxic proteins piling up in the brain. In their article, the scientists suggest that melatonin supplements can improve mild, cognitive impairment and depression. It also seems that melatonin can delay the progression of Alzheimer’s disease, which is the leading cause of dementia.
  • Autism and ADHD
    Patients with autism and ADHD often suffer from circadian rhythm disorders and sleep disturbances. Melatonin supplementation can positively affect autism by improving sleep and improving behavior when people are awake. Melatonin may even have a positive effect on ADHD, but this needs to be studied closer.
  • The heart and circulatory system
    Apparently, daily supplementation with 5 mg of melatonin for two months or more can improve blood pressure and levels of LDL cholesterol in patients with metabolic syndrome, which is an early stage of type 2 diabetes. The scientists mention that melatonin improves sleep and works as a powerful antioxidant by counteracting oxidative stress and inflammation that causes damage to the cardiovascular system. Moreover, melatonin may have a positive impact on insulin sensitivity and blood sugar levels.
  • Cancer prevention and cancer therapy
    Melatonin supplements and their effect on cancer have been studied for at least three decades. High-dosed melatonin supplements seem to suppress tumor growth and improve quality of life. Also, they can improve the effect of chemotherapy. It has also been seen that patients with breast cancer or bowel cancer have circadian rhythm disorders and sleep poorly. Melatonin can help in these cases.
  • COVID-19
    There is currently a lot of scientific focus on whether melatonin can improve the immune defense and help to prevent and treat COVID-19 infections in combination with supplements of other relevant nutrients like vitamin D, selenium, and zinc.
  • Other diseases
    Also, the authors mention melatonin supplementation in connection with diseases like migraines, headache, tinnitus, impaired fertility, endometriosis, PCOS (polycystic ovary syndrome), intestinal disorders, and osteoporosis.

Optimize your own synthesis of melatonin

To optimize your endogenous melatonin synthesis by way of diet and lifestyle, make sure to have special focus on the following:

  • Get enough light during the day and lots of vitamin D
    The powerful ”blue” daylight helps us produce seronotin that is a precursor of tryptophan. Tryptophan is also a precursor of melatonin. Vitamin D from sunlight or from supplements can enhance the effect of melatonin.
  • Avoid ”blue light” at night
    At night when the sun has gone down, orange and red light is more suitable for the body. Blue light from LED and electronic devices is “light pollution” that disrupts the body’s natural melatonin synthesis. It is therefore recommended to turn off such devices at the latest one hour before bedtime, or to use yellow glasses that block out the blue screen light. Exposure to red light in the evening can stimulate the body’s melatonin release, and this technique is used in hospitals
  • Sleep in a dark bedroom
    Buy blackout curtains for the bedroom or use a sleeping mask to keep out the light. Avoid turning on too much light if you need to get up during the night to go to the bathroom.
  • Diet
    Make sure to get plenty of tryptophan from meat, game, and eggs. Also make sure to get enough B vitamins and magnesium so that tryptophan can be converted into melatonin by way of different enzyme processes. Eat an anti-inflammatory diet with plenty of omega-3 fatty acids and many different antioxidants. Certain foods such as cherries (especially the tart ones), oats, bananas, walnuts, corn, tomatoes, peanuts, and mushrooms contain melatonin (albeit in limited quantities)

Melatonin supplementation

If your endogenous melatonin synthesis is still too low, try taking a melatonin supplement. Supplements typically contain 3 mg of melatonin.
If you have sleep disturbances, take 1-2 tablets per day one hour before going to bed. In the case of cancer and other diagnoses, larger doses should be taken but always under the guidance of a health professional


Deanna M. Minich et al. Is Melatonin the ”Next Vitamin D”?: A review of Emerging Science, Clinical Uses, Safety, and Dietary Supplements. Nutrients 2022

Stephanie Watson. All you need to know about melatonin. MedicalNewsToday. 2020

Peter Tougaard. Sygeplejersker får bedre søvn af rødt natlys. Ugeavisen Kolding 2015

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