Melatonin is a hormone produced in the body by the pineal gland from the amino acid serotonin that comes from tryptophan. When darkness hits the retina, the hypothalamus sends signals to the pineal gland to produce melatonin.
Melatonin plays a key role in synchronising circadian rhythms and helps regulate the sleep-wake cycle in mammals. Exposure to light inhibits this process, causing a rapid decline in melatonin synthesis which can lead to insomnia. Artificial lights and computer or mobile phone screens can cause this.
In addition to this function, melatonin is a potent antioxidant that protects the body and brain from free-radical damage. It can help to prevent degenerative brain disorders such as dementia and Parkinson’s disease.
Why should melatonin supplements be avoided?
Supplements are not advised as only 0.5 mg to 3 mg are usually sufficient and more than 10 mg may cause toxicity symptoms. In scientific studies it has been found that prolonged use of melatonin, as a sleep aid in patients with insomnia, was associated with increased risk for heart failure.
Symptoms of melatonin toxicity
- Confusion
- Dizziness
- Drowsiness
- Fatigue
- Headaches and migraine
- Hypotension
- Hypothermia
- Nausea
- Nightmares
- Tachycardia
Natural sources of melatonin in alphabetical order
- Almonds
- Bananas
- Cashew nuts
- Cherries (sour)
- Grape skins
- Kiwi fruits
- Olive oil
- Pineapples
- Pistachio nuts
- Sesame seeds
- Tomatoes
- Walnuts
- Wine
NOTE: Melatonin is also present in some animal products such as salmon and eggs and in rice and some grains but is destroyed by cooking.
Related subjects
- A-Z of nutrients
- Brain and mental health disorders
- Dementia
- Free radicals
- Insomnia
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