The production and release of melatonin from the pineal gland occurs with a clear daily rhythm, with peak levels occurring at night. Once produced, it is secreted into the blood stream and cerebrospinal fluid (the fluid around the brain & spinal cord) and conveys signals to distant organs. Melatonin is carried by the circulation from the brain to all areas of the body. Tissues expressing proteins called receptors specific for melatonin are able to detect the peak in circulating melatonin at night and this signals to the body that it is night-time. Night-time levels of melatonin are at least 10-fold higher than daytime concentrations.
How is melatonin controlled?
In humans and other mammals, the daily rhythm of pineal melatonin production is driven by the ‘master’ circadian clock. This ‘clock’ is in a region of the brain called the suprachiasmatic nuclei, which expresses a series of genes termed clock genes that continuously oscillate throughout the day. This is synchronised to the solar day via light input from the eyes. The suprachiasmatic nuclei link to the pineal gland through a complex pathway in the nervous system, passing through different brain areas, into the spinal cord and then finally reaching the pineal gland. During the day, the suprachiasmaticnuclei stops melatonin production by sending inhibitory messages to the pineal gland. At night however, the suprachiasmatic nuclei are less active, and the inhibition exerted during the day is reduced resulting in melatonin production by the pineal gland.
Benefits Of Melatonin
Reverses Circadian Rhythm Sleep Disorders: Melatonin has the ability to shift biological rhythms. This makes it useful in the treatment of various circadian rhythm sleep disorders, such as advanced and delayed sleep phase disorders, jet lag and shift-work disorder.
- Improve Insulin Function: Low night-time secretion of melatonin nearly doubles the risk of developing diabetes. In fact, melatonin improves insulin balance and protects insulin-producing cells in the pancreas from cell death. It can be used as a supporting therapy for treating prediabetes, diabetes type 2, Polycystic ovary syndrome (PCOS), and insulin resistance.
- Melatonin for Mood: Improve Feelings of Wellbeing: Importantly, Melatonin supplements can also be used to improve mood and feelings of well-being. This is through two key mechanisms. Firstly, there is a strong relationship between sleep and mood. Studies have found that even a small lack of sleep can result in decreased mood and, conversely, better sleep promotes a good mood. Furthermore, a better mood helps to improve sleep quality while a bad mood often results in decreased sleep.
- Potential Treatment for Breast and Prostate Cancer: Several studies suggest that low melatonin levels may be associated with breast cancer risk. To determine melatonin’s effectiveness at stopping tumor growth, one group of researchers evaluated the action of melatonin dosage on the growth of breast tumors in vitro (using human cancer cells) and in vivo (using mice). The researchers found that melatonin may inhibit tumor growth and cell production, as well as block the formation of new blood vessels in estrogen receptor-negative breast cancer models. This 2014 research shows melatonin’s potential as a therapeutic agent for breast cancer.
- Heart Disease Helper: Multiple studies suggest that melatonin has heart-protective properties. Specifically, research shows that when it comes to cardiovascular health, melatonin has anti-inflammatory and antioxidant effects. It also can help lower blood pressure and cholesterol. It seems to have cardioprotective properties via its direct free radical scavenger activity. Overall, the protective abilities of melatonin may be able to help reduce and treat cardiovascular diseases
- Support Eye Health: Healthy melatonin levels may support eye health. It has powerful antioxidant benefits that could help lower the risk of eye diseases,
- Seasonal Depression: Seasonal depression is commonly known as the “winter blues” or seasonal affective disorder (SAD). It may affect up to 20% of adults. Some evidence shows that seasonal depression is affected by changes in light and sleep cycles. In turn, melatonin could possibly help reduce symptoms of seasonal depression by helping with the sleep cycle.
