Human life is subject to a certain biological rhythm, through which the precise regulation of the work of various organs and systems is carried out. Melatonin, which is secreted in the brain and affects sleep, plays a fundamental role in the complex system of regulating this rhythm.
Melatonin is a hormone that is strongly influenced by “dark” and “light” therapy and can be used as a means to improve sleep. It is preferred to some drugs because it is not addictive.
Just as all protein articles acknowledge that a high-protein diet is more important than the intake of powders in particular, so melatonin articles must recognize that the body needs a proper sleep rhythm.
It is possible that some of the long-term benefits of melatonin are due to the normalization of sleep and result from this fact, rather than from direct supplementation with melatonin.
Table of Contents
What is melatonin?
Melatonin (5-methoxy-N-acetyltryptamine) is a peptide hormone and neutrotransmitter present in all living things (from algae to humans) at levels that vary in the daily cycle. In higher animals, it is produced by pinealocytes (a type of cell) in the pineal gland (located in the brain), as well as by the retina and gastrointestinal tract. It is synthesized from the amino acid tryptophan by the synthesis of serotonin by the enzyme 5-hydroxyindole-O-methyltransferase.
Melatonin is produced in the pineal gland (small gland in the brain) under the baton of serotonin (one of the most important neurotransmitters). Like a vampire, melatonin appears in the blood only at night and disappears during the day. At dusk, the pineal gland begins to gradually increase melatonin secretion, which reaches its maximum in complete darkness.
In the morning, light activates the optic nerve, with the generated impulse passing through the spine and higher conduction pathways to reach the pineal gland, which blocks the synthesis and secretion of melatonin. Thus, in practice, a metronome works, regulating the activity of the central nervous system.
Receiving continuous impulses through the optic nerve, the pineal gland is probably able to regulate the activity of various organs and systems and stimulate the transition to “economy mode” when it is dark, which significantly reduces the body’s energy expenditure. A key element in this regulatory mechanism is also melatonin. Melatonin is found naturally in a number of plants in sufficient bioactive doses. Among the best sources of melatonin are tomatoes, walnuts, barley, rye, strawberries, olive oil, raw cow’s milk, wine, beer and cherries.
How does melatonin work?
It was found that the synthesis of melatonin in the human body plays an extremely important role in controlling the circadian rhythm of alertness and sleep and the associated changes in the secretion of various hormones (cortisol, testosterone, growth hormone).
Melatonin is a fundamental regulator of the cyclical rhythms of the human body. It shows a 24-hour model of synthesis and release. Its natural bioavailability for a long period of time (5-6 hours) during the night determines the effect on the cyclic system of biological rhythms.
As already mentioned, melatonin regulates the alertness-sleep cycle and synchronizes biorhythms. This precise rhythm, individual for each person, can derail if there are disturbances in melatonin secretion.
When in sufficient quantity, melatonin slightly lowers a person’s body temperature – thus reducing energy consumption and accelerating the regeneration of cells that are not active during the sleep phase.
It is believed that melatonin is one of the most powerful antioxidants known to us, which act both at the level of the cell membrane and inside the cell itself. In the course of evolution, man has lost his ability to produce some powerful antioxidants, such as beta-carotene and vitamin C in his body, but has retained other antioxidants (such as melatonin) that inactivate free radicals (a great threat to the body) and thus form a powerful defense system against them.
For example, the brain, made up of 50% adipose tissue, 1/3 of which is unsaturated fatty acids, is very sensitive to free radicals. The pineal gland, located at the base of the brain, synthesizes melatonin, which is the “last frontier” against free radicals attacking the brain. Melatonin also lowers the level of “bad” LDL-cholesterol, protects against some cancers and stimulates the immune system.
Serum levels and metabolism
Studies on a number of models associated with insomnia or difficulty falling asleep have shown that small doses of 0.3 or 0.5 mg are as effective as ten times higher doses. It was also found that a “super” dose of 20 mg had a weaker effect than the conventional dosage.
Detection of serum melatonin peaks is extremely difficult, varying with each test. There is not much difference between the different dosages, but in all cases the serum concentrations of melatonin increase several times compared to each physiological concentration. Doses of 3 to 5 mg increase the concentration more and slow down the half-life.
The half-life of melatonin is only 24 minutes, and its levels in the blood remain stable for up to 150 minutes after ingestion. The half-life does not differ between small and large doses. The same applies to the occurrence of serum peaks, which occur after 45-75 minutes after ingestion.
There is a study according to which the injection of melatonin in the nose may be far more effective than standard oral administration.
Melatonin is metabolized and rapidly eliminated from the body. Its metabolism is accelerated by aromatization and some habits, such as smoking, increase its elimination from the body.
Melatonin and age
Peripheral blood melatonin levels are different in young and adult individuals. It has been proven that with age the circadian systems in the human body “break down”. As with most hormones, melatonin levels drop dramatically as they age – in an 80-year-old, for example, serum levels are only 10% of those in 20-year-olds.
The consequence of this is a significant change in a number of vital parameters. Especially the fact that the sleep-wake cycle is negatively affected, the temperature of adults does not drop at night, which means that the recovery processes of tissues and organs cannot take place.
Proven and potential benefits in humans
Sleep and calm
Melatonin is best known for its properties for improving sleep and treating insomnia. It is for this reason that it is used as a reference substance for testing other similar ones. The most commonly used dose is 3 mg with a gradual release. The main mechanism of action is associated with the reduction of sleep time, and melatonin has benefits in completely healthy individuals. Some studies claim that melatonin even improves sleep quality, but this has not been proven in healthy individuals.
However, the same does not apply to adults and children suffering from insomnia, in whom melatonin has a positive effect on the quality of sleep.
This also applies to people who suffer from migraines or subjective tinnitus, which lacks an external source, as well as schizophrenics.
The effect of melatonin on lowering body temperature has been proven, which also has its benefits for easier sleep. Melatonin has the strongest effect in people over 55 or suffering from insomnia.
Melatonin also improves sleep when there are external or internal factors for its poor quality. The external factors are day and night cycles, and the internal factor is the internal clock of each individual.
When internal or external factors are not “tuned”, melatonin helps to bring balance. One of the most valuable benefits of melatonin is for travelers and is its ability to regulate circadian rhythms during long journeys in different time zones.
This is evidenced in a huge meta-analysis of ten different studies. Taken before travel or according to hourly doses, melatonin regulates the circadian rhythm and avoids the specific state of fatigue and difficulty falling asleep when passing several time zones. An even more impressive fact is that this phenomenon also applies to night shifts. The effect of melatonin on sleep is often associated with exposure to light. Melatonin works best with exposure to bright light in the first part of the day, but does not go well with exposure to bright light before bedtime.
Stomach problems
One of the most impressive effects of melatonin is associated with stomach function. Melatonin successfully increases the serum levels of gastrin, whose low levels occur in people with gastric ulcers, which is associated with the healing properties of melatonin in this regard.
All studies so far show that melatonin has strong protective properties against ulcers, and the effect manifests itself, and the results demonstrate complete recovery. Melatonin has a protective effect against the harmful effects of some bacteria and aspirin.
Taking melatonin at bedtime reduces the symptoms of gastroesophageal reflux disease (GERD), as well as palpitations in reflux.
Nervous system
Melatonin affects some neurotransmitters in the body. For example, it stops the increase in adrenaline and noradrenaline levels in stressful situations, but does not completely eliminate them. In stressful situations, melatonin also reduces adrenaline levels.
Melatonin reduces blood flow to the brain and is thought to be beneficial in migraines, although this effect is controversial and not fully proven. It is believed that melatonin may have its benefits, especially in improving the quality of sleep in people with migraines.
There is a theory that melatonin may help with some depressive conditions, especially those associated with changes in daylight in winter. Melatonin together with light therapy helps to normalize the circadian rhythm in winter and improve depression.
The neurological benefits of melatonin have also been linked to improved memory. It is possible that melatonin helps to improve memory markers in the elderly, but so far the data are based only on combinations with other substances. However, melatonin alone improves the memory of young individuals in stressful situations.
Cardiovascular system
Small doses of 1-2 mg of melatonin dramatically lower blood pressure in men and women, which is associated with lower adrenaline. The degree of reduction in blood pressure varies with activity and passivity, and it is assumed that such a reduction may not be relevant in every situation. In one study in individuals with metabolic syndrome, melatonin successfully lowered diastolic and systolic blood pressure, and this reduction was not associated with body weight.
Melatonin further improves blood flow and has vasorelaxing properties. In this case, it affects the blood flow to the limbs and kidneys, but not the cerebral one.
Compared to triglycerides and cholesterol in the blood, melatonin does not have a positive effect, but an interesting effect has been found when taking melatonin before training, in which case the peptide hormone enhances the lowering of triglycerides.
Peripheral organs (eyes and ears)
Melatonin has a positive effect on blood pressure in the eyes through the melatonin receptor. This effect is also associated with lower adrenaline. There was a significant reduction up to two hours after oral administration.
The benefits of melatonin for the eyes do not end there. Melatonin levels in the eyes of glaucoma patients have been found to be significantly lower in the evening, with melatonin in this case helping to improve the condition or at least stop it from getting worse.
As already mentioned, melatonin also has benefits for the state of subjective tinnitus. Although it improves sleep and sleep quality in patients with this disease, it does not directly affect treatment.
Effects on fats
So far, there is no study that confirms the direct effect of melatonin on the amount of body fat and body composition. However, there is a study in humans that found that melatonin, when taken for more than a week, increased circulating levels of the hormone leptin without any changes in diet.
This increase persists after the third week of use, and in people with “oily” liver, the increase is even more significant. Leptin secretion has been shown to be insulin-dependent and this process is stimulated by melatonin.
The same results were confirmed in tests on rats. The percentages differ significantly due to the association of leptin with circadian rhythm. Animal testing goes even further, finding fat loss. The mechanism is unclear, assuming that this can be done by burning fat directly or by suppressing lipogenesis.
These findings have no practical benefit so far in healthy individuals, but melatonin intake slightly improves body mass index in individuals with metabolic syndrome. It is possible that melatonin helps to burn fat in certain circumstances, especially sleep disorders or because of the positive effect on blood pressure and antioxidant activity.
Impact on physical activity
Melatonin has no physical effect on exercise, but can have a neural effect. It was found that evening intake of melatonin does not adversely affect training in the morning, but taking melatonin up to 3 hours before physical activity leads to calming and increasing the reaction time, without adversely affecting endurance and strength in aerobic exercise.
Pre-workout melatonin intake increases antioxidant activity and reduces blood triglyceride growth and lipid peroxidation.
Melatonin and hormones
Although a link has been found between melatonin and female sex hormones, tests on women after breast cancer surgery have found no effect on estrogen, specifically “bad” estrogen. However, melatonin affects aromatization.
We can conclude that this effect is more related to advancing age, in which melatonin deficiency is associated with increased aromatization, and this process can be regulated. However, melatonin cannot be used as a therapy to regulate aromatization and estrogen.
Melatonin does not particularly affect male sex hormones. Although it suppresses testosterone in the testes of rats, it has no similar effect in humans and does not affect testosterone and luteinizing hormone levels in healthy men.
The only benefits of melatonin in this regard are that its regular intake can reduce testosterone drops after prolonged exercise. Melatonin has a positive effect on constant prolactin levels, but only after regular use for 5 days. Unlike other hormones, prolactin is not affected by melatonin in a single dose.
Regular melatonin intake in the evening slightly increases cortisol levels throughout the day in healthy and young men. Cortisol is more strongly affected by melatonin when taken in high doses in the morning by women who have had breast cancer surgery. In these cases, cortisol increases significantly in the evening, and then its levels are suppressed by high estrogen levels.
Among hormones, melatonin has the strongest effect on growth hormone. A single dose between 0.5-5 mg successfully increases growth hormone levels by 16-17% within 150 minutes.
This effect has been observed at rest in healthy men. Analyzes show that melatonin does not directly increase hormone levels, but exacerbates the sensitivity of the pituitary gland to its action.
Data on the effects of melatonin on growth hormone after exercise are conflicting. Two studies found that melatonin significantly increased growth hormone after exercise, but a third study found that it had the exact opposite effect. So far there is no definite answer.
Effects on cancer metabolism
One meta-analysis concluded that one year of melatonin use reduced the risk of death in patients with solid breast tumors. The risk is reduced by nearly 25%. Melatonin actually provides a general protective effect and reduces deaths. One hypothesis is that poor circadian rhythms and low levels of melatonin in the body are part of the reasons for the development of breast cancer. Other hypotheses link the action of melatonin to its effect on processes such as aromatization and certain intracellular mechanisms.
Melatonin has also been tested for cancer of the intestinal tract, but even in combination with fish oil, it does not directly affect the metabolism of the disease. On the other hand, both supplements help to gain weight in sick patients.
Longevity
Melatonin and the pineal gland are associated with life expectancy. With age, melatonin levels in the body decrease and it is believed that additional supplementation can help longevity.
The use of melatonin is associated with effects on pro-inflammatory cytokines in cardiac tissues, which can increase life. A similar protective effect is manifested in the pancreatic and liver tissues. Animal tests also show an anti-aging effect on the skin.
Proven and potential benefits in animals and in vitro
- It successfully suppresses the secretion of dopamine in neurons. It has a particularly strong effect when the release of dopamine is due to the action of beta agonists such as ephedrine;
- It functions as a neuroprotector due to its antioxidant properties, by suppressing the pigmentation of beta-amyloids and the influence on the mTOR mechanism;
- It has an anti-adrenogenic effect in cardiac tissues, reducing cAMP production by 34%;
- Strong antioxidant effect. It also stimulates certain antioxidants in the body, such as superoxide dismutase (SOD) and catalase. It also protects DNA from mineral damage and its level of protection is comparable to that of resveratrol, alpha lipoic acid and green tea;
- Affects fats, which can be done by burning fat directly or by suppressing lipogenesis;
- It has a protective effect on the skin due to its antioxidant activity. The benefits have only been studied in vitro;
- By reducing oxidative stress, melatonin can have a positive effect on hair loss caused by androgen exposure. In-vitro studies show positive results in stimulating hair growth in these cases, but the only human study cannot be found online and is controversial;
- Anti-cancer properties through the impact on various mechanisms, but the practical significance in humans is unclear.
Dosage and method of use
Melatonin is not a hypnotic, it is not addictive – it simply synchronizes biorhythms and ensures restful and long sleep. Doses between 0.5 mg and 5 mg have been found to work to improve sleep patterns.
Our recommendation is to start with the minimum dose and gradually increase in the absence of effect. The benefits of melatonin are not dose-dependent, so a higher dose does not mean a stronger effect. Only a higher dose would benefit slightly higher growth hormone peaks.
To ensure better action, it is recommended to take one tablet a day, which should be taken with a glass of water in the evening up to 30 minutes before bedtime. The tablet should not be chewed. Exceeding the daily dose is not recommended. Although melatonin is found as a dietary supplement, self-medication is not recommended before a medical diagnosis!
Side effects and contraindications
Melatonin is one of the safest and non-toxic substances. Shock doses of up to 500 mg, whether taken orally or intravenously, have no intoxicating effect. It is not toxic in adults over 60 years of age. Doses up to 5 mg daily are also safe for children over 5 years of age, and it is possible to take them by younger children, but only after consultation with a pediatrician. Melatonin is not addictive. Several detailed, large-scale studies have found that even with a constant intake of 6-12 months, it is not addictive.
There are hypotheses that it is possible to have the opposite effect when stopping melatonn supplementation. At this stage, it has been shown that doses up to 2 mg should not have similar effects, but it is assumed that long-term use of higher doses may have side effects after stopping melatonn. The most established hypothesis so far is that the possible reason is not the cessation itself, but the fact that the body returns to its previous improper sleep pattern.
With what to combine melatonin?
To improve sleep, melatonin can be used with other similar supplements such as gaba, 5-HTP, L-Theanine, zma and L-Tryptophan. Melatonin acts on enzymes that inhibit the transformation of L-Triprofan into 5-HTP, so their combination is recommended.
It also has an antioxidant effect. It is recommended to be combined with other antioxidants such as vitamin C, alpha lipoic acid and resveratrol. Combination with green tea is not recommended because melatonn and the antioxidant EGCG act as antagonists.
At this stage, it is not clear whether alcohol interferes with melatonn supplementation.
Where can we find melatonin?
Melatonin is one of the most affordable nutritional supplements on the market and as an economical one, almost every brand offers its own version. You can find melatonn in food supplement stores or pharmacies.
Most often, melatonn is available on its own, and in most formulas on the market there are encapsulated or tablet versions with doses of 3 to 5 mg. Higher dosages are rarely offered. Gradual release formulas are also preferred. Sometimes melatonn is also present in complex formulas to improve sleep. A similar formula is PN Z-Max, which combines classic ZMA with melatonn.
Sources used :
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Waldhauser F, et al Bioavailability of oral melonin in humans . Neuroendocrinology. (1984)
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Nave R, Peled R, Lavie P Melatin improves evening napping . Eur J Pharmacol. (1995)
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