What is melatonin?

Melatonin is a natural hormone that’s mainly produced by your pineal gland, which is a tiny gland in your brain. Your pineal gland is part of your endocrine system. The full impact of melatonin in humans isn’t totally clear, but most research shows it helps to synchronize circadian rhythms in different parts of your body. Circadian rhythms are physical, mental and behavioral changes that follow a 24-hour cycle. The most important and well-known of these circadian rhythms is your sleep-wake cycle. These natural processes respond primarily to light and dark. Your pineal gland secretes the highest levels of melatonin during the night and minimal amounts during the day.

Melatonin’s effect on sleep

Your pineal gland releases the highest levels of melatonin when there’s darkness and decreases melatonin production when you’re exposed to light. In other words, you have low levels of melatonin in your blood during the daylight hours and peak levels of melatonin during the nighttime. The longer the night, the longer your pineal gland secretes melatonin. Because of this, melatonin has often been referred to as a “sleep hormone.” While melatonin isn’t essential for sleeping, you sleep better when you have the highest levels of melatonin in your body. However, several other factors contribute to your body’s ability to sleep and the quality of the sleep you get. As your pineal gland receives information about the daily light-dark (day-night) cycle from the retinas in your eyes and then releases melatonin accordingly, people with blindness who can’t detect light usually have irregularly synchronized melatonin cycles leading to circadian rhythm disorders.

Other effects of melatonin

Melatonin also interacts with biologically female hormones. Research has shown that it helps in regulating menstrual cycles. Pineal melatonin can also protect against neurodegeneration, which is the progressive loss of function of neurons. Neurodegeneration is present in conditions such as Alzheimer’s disease and Parkinson’s disease. Researchers have found that people who’ve had their pineal gland surgically removed (pinealectomy) experienced an accelerated aging process. Because of this, some scientists think natural melatonin may have anti-aging properties.