Primarily synthesized in the pineal gland, melatonin is a hormone produced and released in relation to the circadian rhythm. To a lesser extent, melatonin is also synthesized in the heart, liver, placenta, skin, kidney, gut, and more. Melatonin secretion from the pineal gland decreases as we age.
Melatonin is involved with the promotion of sleep, timing of other circadian functions, immune regulation, and modulation of pituitary and adrenal hormones. The release of melatonin is regulated by light exposure. Melatonin concentrations rise as light fades prior to darkness, peak during darkness, and fall when exposed to light to promote wakefulness. Evening artificial light can have the same effect as sunlight, which explains how it can disrupt the rhythmic release of melatonin.
The primary function of melatonin, however, both in health and disease, is associated with its antioxidant and anti-inflammatory effects. A potent antioxidant with immune-enhancing effects, melatonin also plays a role in blood pressure and cardiovascular regulation, detoxification, and offers neuroprotective benefits. Given these important mechanisms, therapeutically, melatonin may also provide protection against a number of illnesses including cancer and neurodegenerative conditions.
Sleep
Studies suggest that melatonin is helpful to decrease sleep onset and improve delayed sleep phase, meaning it helps you to fall asleep and achieve deeper sleep sooner. It does not appear that melatonin is beneficial in helping you stay asleep. Data suggest that for maximal effect, oral melatonin should be taken approximately 40 min before attempting to sleep.
Cancer
Melatonin has proven to be highly involved in the etiology, development, metabolism, metastasis, and therapy of various cancers. With cancer, melatonin acts to inhibit tumor cell growth and proliferation, modulates the metabolism of cancer cells, promotes apoptosis (or cancer cell death), has antiangiogenic effects, enhances the effects of anticancer medications, and reduces the side effects of radio- and chemotherapy protocols. Many studies have shown that the combination of melatonin and conventional drugs improves the treatment effects. Melatonin also stimulates the synthesis of other antioxidants. Along with its free radical scavenging properties, melatonin protects the mitochondria against oxidative stress
Research suggests that melatonin offers beneficial actions against hematological cancers. The antiestrogenic action of melatonin could also limit the proliferation of hormone-sensitive breast cancer. Furthermore, low melatonin levels may increase the risk of prostate cancer. Preclinical research suggests that melatonin may be of particular benefit for those on androgen deprivation therapy. Additionally, melatonin protects against doxorubicin-induced cardiotoxicity.
The inhibitory effects of this hormone can be achieved as a single therapeutic agent or in combination with other therapies. Melatonin acts as an adjuvant treatment for cancer working synergistically with many conventional cancer drugs.
Bone Density
Interestingly, the possible association of melatonin with aromatase inhibitors could reduce the risk of osteoporosis described with treatment with this family of drugs. Melatonin promotes osteoblasts, which are responsible for bone formation. In this trial, postmenopausal women with osteopenia who took 1-3 mg melatonin daily for 6-12 months improved bone mineral density and decreased the risk of fractures.
Inflammation
Growing evidence supports the anti-inflammatory role of melatonin, both in acute and chronic inflammation processes.
Cardiovascular Health
Vast preclinical evidence indicates a cardioprotective and cardiovascular protective effect from melatonin. Melatonin protects the vascular endothelium, regulates lipid and glucose metabolism and modulates blood pressure. Helping to reduce atherosclerosis, and inhibit thrombosis, melatonin functions to reduce oxidative stress and inhibit inflammation. Several studies have demonstrated that melatonin has an antihypertensive effect. In patients with nonalcoholic fatty liver disease, treatment with melatonin (2 × 5 mg/day) for 14 months significantly reduced levels of triglycerides and LDL cholesterol compared with controls.
Body Weight
Several clinical trials have confirmed the usefulness of melatonin for obesity treatment. In one trial, postmenopausal women treated with either melatonin (1–3 mg nightly) or placebo for 1 year reported a significant decrease of fat mass and an increase of lean mass in the melatonin group compared to placebo.
Neurodegenerative Diseases
Melatonin has been found to exhibit neuroprotective effects on the central nervous system. Due to its antioxidant, anti‐inflammatory, and anti‐β amyloid aggregation effects, melatonin prevents synaptic dysfunction, neuronal loss and cognitive impairment. Several double-blind placebo-controlled studies with small samples suggest that melatonin (3-5 mg immediate-release or 2 mg prolonged-release) has a positive impact on cognitive function and sleep disorders associated with Alzheimer disease. However, other studies report contradicting results.
Sources of Melatonin
While in small amounts, melatonin is found in a wide variety of foods, from fungi to animals and plants. Eggs and fish provide the greatest amounts of melatonin among animal foods, whereas in plant foods, nuts, particularly pistachios, contain the highest content of melatonin. Some kinds of mushrooms, cereals and sprouted legumes or seeds are also good dietary sources of melatonin. More commonly, melatonin is found as a dietary supplement ranging from 500 mcg to 20 mg.
Bottom Line
Melatonin has been well studied due to its antioxidant, anti-inflammatory, and immunomodulating benefits. Melatonin is generally safe and well-tolerated. Doses of 1-5 mg melatonin daily are common for managing insomnia, and up to 20 mg daily is often suggested for its anticancer effects. Most studies related in bone density, body weight, neurodegenerative diseases used 5 mg or less daily of melatonin.
With more holidays around the corner, do your best to take care of your mind and body.
In Health,
Natalie