That remarkable MELATONIN

Sooner or later, we all encounter the topic of melatonin—the remarkable compound best known as a supplement used to improve sleep quality and help with falling asleep. In fact, melatonin is the only neurotransmitter secreted by our pineal gland. This small, pea-sized gland is located deep in the center of the brain, behind our eyes which it is connected to.

Based on the sight information, the pineal gland releases the highest amounts of melatonin during the darkest hours of the night ( 1 -5 a.m.). It is therefore easy to understand how artificial lighting and screen exposure at night can confuse the signals it receives. This leads to disrupted melatonin secretion and disturbances of the normal circadian rhythm (the day–night, wake–sleep cycle). But what other effects does this neurohormone have, and what are the benefits of taking it as a supplement?

Melatonin was first observed in 1917 as an unknown compound in the pineal glands of cows. When extracts were applied to frog skin, they caused changes in skin color. It was not until forty years later that an American dermatologist isolated and named melatonin, initially with the idea of using it to treat various skin conditions.

It was already known at that time that melatonin is produced in much higher amounts at night—more than eight times higher. In study participants, the peak secretion occurred between 10 p.m. and 7 a.m., meaning while sleeping and in dark conditions.

In addition to screen exposure, frequent night shifts pose a significant problem. They are associated with an increased risk of heart disease, digestive issues (ranging from IBS to inflammatory bowel disease), sleep disorders, and even a higher incidence of certain cancers. If changing jobs is not possible, night-shift workers are advised to take melatonin supplements in the early morning hours (between 1:00 and 4:00 a.m.) and to compensate with daytime sleep in softly lit conditions—rather than in complete darkness.

Melatonin has also been shown to have very strong antioxidant properties—almost twice as powerful as one of the most well-known antioxidants, vitamin E. It not only promotes the production of antioxidant enzymes that remove free radicals (harmful compounds that damage DNA), but also stimulates immune system cells.

Melatonin in the bloodstream helps reduce chronic inflammation (for example in obesity, metabolic syndrome, and insulin resistance) and prevents the oxidation of LDL, the so-called “bad cholesterol.” As a result, LDL becomes less likely to adhere to blood vessel walls, reducing the formation of atherosclerotic plaques—the most common cause of angina pectoris and heart attacks.

NEUROPROTECTIVE EFFECTS

Through its strong antioxidant action, melatonin plays a particularly important role in protecting the brain, which contains a high density of melatonin receptors. Numerous studies have shown that melatonin supplementation has a protective effect in stroke, reducing the extent of affected brain tissue. In Alzheimer’s disease, melatonin use has been shown to improve continuous nighttime sleep.

Studies have also reported an increase in hippocampal volume—a brain region crucial for learning and memory—after six months of melatonin supplementation. While melatonin shows potential preventive effects in reducing the risk of developing neurological disorders, the most important form of prevention remains regular, high-quality sleep.

MEN’S AND WOMEN’S HEALTH & FERTILITY

Considering that even occasional disruptions of regular sleep can lead to menstrual cycle irregularities, it is not surprising that melatonin is closely linked to women’s health and fertility. Positive effects of melatonin supplementation have been observed in polycystic ovary syndrome (PCOS), where it has been shown to reduce symptoms such as hirsutism (excess facial hair). A 2013 study found that after eight weeks of melatonin use, women with endometriosis experienced a significant reduction in pain.

The role of melatonin in fertility should not be overlooked, and it is often recommended for women experiencing difficulties with conception, either as a standalone supplement or in combination with myo-inositol. Notably, the follicular fluid surrounding the egg cell just before ovulation contains up to three times higher levels of melatonin than blood, and placental cells are also known to secrete increased amounts of melatonin.

In men, in vivo (human) studies have demonstrated improved sperm motility and integrity with melatonin supplementation. After 45 days of use, increased melatonin concentrations were observed in seminal fluid. Acting as a powerful antioxidant, melatonin helps reduce sperm DNA damage, improves sperm function and penetration ability, and overall enhances sperm quality—thereby increasing the chances of conception.

FIGHTING THE BREAST CANCER?

Given its strong antioxidant properties, melatonin quickly became a subject of research as a supportive agent in cancer care. Several studies have linked higher melatonin levels with a stronger immune response against tumors. One study suggested that melatonin therapy may reduce the number of receptors involved in the invasive spread of ovarian cancer. As a potent antioxidant, melatonin enhances the activity of enzymes responsible for DNA repair, which may slow tumor progression and reduce the toxicity of chemotherapy and radiotherapy.

This effect has been associated with fewer side effects when melatonin is used alongside chemotherapy, such as oral inflammation, bone marrow suppression, weakness, and fatigue, while also improving sleep quality. Several well-designed studies have shown a higher incidence of cancer in women who work night shifts over long periods. In one such study, melatonin levels were measured in the urine of nurses frequently exposed to night work; those with lower melatonin levels had a higher risk of developing breast cancer later in life.