Sleep issues such as insomnia as well as other lifestyle-induced sleep disorders are continuing to increase in prevalence. Individuals experiencing sleep difficulties are further at risk of psychiatric conditions such as depression, anxiety and substance abuse. Thus, improving sleep and enhancing sleep quality is of utmost importance. Understanding key contributors to the body’s sleep process are essential in order to effectively improve sleep. One of the key physiological factors in the body’s sleep cycle is the hormone melatonin.
What is Melatonin?
Melatonin is the primary hormone manufactured by the pineal gland of the brain and is known to act as a powerful “chronobiotic”, which means that it functions to maintain a normal circadian rhythm. It is the key hormone that signals to the body that it is nighttime and it is released exclusively at night in accordance with the circadian rhythm, with serum levels of melatonin being highest prior to bedtime.
Melatonin production is inhibited by exposure to light and is stimulated during periods of darkness. The main signal for the pineal gland to produce melatonin is sensed through the neural pathways connected to the retina of the eye. If the retina senses light, production will be inhibited, while the opposite will be true as the retina senses darkness. A common modern concern that factors into insufficient production of melatonin is exposure to blue light from digital devices. Sleep disturbances due to excessive use of cell phones, tablets, and computers, especially at night, are a real issue for many people. Changing our device use habits by not using them close to bedtime and ensuring our bedrooms are sufficiently dark create an ideal environment for secretion of melatonin, which can signal that it’s time to sleep.
Melatonin levels have been found to decrease with age, but several other contributors to low levels of melatonin exist. These including medications that suppress melatonin (including NSAIDS, beat-blockers, aspirin, and others) as well as factors that lead to poor sleep hygiene, including consumption of alcohol, caffeine and nicotine.
Addressing the factors in our environment that impact our sleep, as well as other health issues that are present, is a first step in addressing issues we experience around poor sleep. However, research shows that externally supplemented melatonin is effective at establishing and maintaining a proper circadian rhythm as well as improving sleep quality and duration.
Melatonin Dose for Sleep
Supplemental melatonin works several ways to improve sleep. Administered orally, it has been shown to have both sedative and hypnotic effects with melatonin dosage of between 0.3mg to 5.0mg. Taken before bedtime, even low dosages have been found to induce sleep, accelerating sleep onset, improving sleep maintenance, and enhancing sleep quality.
In the brain, melatonin supports the effects of GABA, a key neurotransmitter that facilitates relaxation and relieves anxiousness. Furthermore, melatonin is a phase-shifting hormone. While exposure to light through the eyes is the primary regulator of the circadian rhythm, melatonin supplementation 1-2 hours before 9 PM can effectively advance the sleep phase, causing a shift in the circadian rhythm.
Clinical trials using melatonin for sleep have used various melatonin dosages; however, many good studies have used a melatonin dosage between 1 and 2.5 mg per night. In addition, studies have found that sustained release melatonin or those that deliver the hormone over time are most effective for improving overall sleep onset, sleep duration, and sleep quality, while limiting any daytime grogginess from taking this supplement.
Clearly, melatonin is beneficial for resetting our circadian clock and allowing us to sleep better. Melatonin is an effective sleep aid and addresses how to improve sleep quality. However, the benefits of this supplement don’t end with sleep. Recent research highlights the effects of melatonin on immune function.
Melatonin Benefits for the Immune System
Given the current climate where immune challenges abound, scientists have been leaning on therapeutics that have shown promise in the past on multiple levels of the immune system. One of these is melatonin. The immune benefits of melatonin are increasingly being explored, and what is clear from this research is that this hormone does much more than just support sleep. Studies have highlighted the antioxidant, free radical neutralizing, immune modulating, and anti-inflammatory effects of melatonin.
One of the major issues with certain viral infections is not the direct effect of the virus on the immune system; rather, the way our immune system responds and wreaks havoc on the body can be more detrimental. One of these phenomena is what researchers term the “cytokine storm”. This is defined as an upregulation of pro-inflammatory cytokines, which are chemical messengers of the immune response, leading to activation of neutrophils, macrophages and histamine containing mast cells. Uncontrolled and unbalanced activity of these cells on the body result in damage to key organs and systems and uncontrolled inflammation. Melatonin may effectively counteract this inflammation through several pathways, resulting in a reduction of pro-inflammatory cytokines being released. Moreover, melatonin can shift the balance more favorably towards an anti-inflammatory effect, resulting in protection of key organs and a balanced immune response.
During this exaggerated inflammatory immune response, an excess of free radicals is created. It turns out that melatonin can counteract these free radicals through its potent antioxidant activity. Melatonin counteracts free radicals in three unique ways: 1) Melatonin acts directly as an antioxidant and powerful free radical scavenger; 2) Melatonin undergoes metabolism to byproducts that have high antioxidant activity; 3) Melatonin stimulates the production of antioxidant enzymes, while inhibiting the production of pro-oxidant enzymes. Studies also indicate that the antioxidant prowess of melatonin is superior to the well-regarded antioxidants vitamins C and E.
Further research indicates that melatonin is directly involved in the control of antiviral and other immune pathways in the human immune system, while providing added protection to cells as a mitochondrial antioxidant. Interestingly, melatonin is abundant in the mitochondria of cells and can even be synthesized there. As immune challengers such as viruses initiate damage to cells, melatonin counteracts this to prevent cellular senescence and death.
Furthermore, melatonin exerts protection to nerves and brain tissues. Many viruses can adversely affect brain function and lead to neurological complications. Melatonin’s neuroprotective ability has been illustrated in individuals with early-stage cognitive decline. In these studies, nightly administration of melatonin led to improvements in cognitive performance, while promoting better sleep. Those taking melatonin had significantly improved cognitive performance and enhanced mood, indicating a protective effect of this hormone against brain degeneration.
This research strongly indicates the link between melatonin and immune system function. The research on sleep and immune function further solidifies the connection between the two areas and how melatonin plays an integral role in improving the function of both. Healthy sleep and a robust immune response go hand in hand; melatonin is an important link bringing the two areas together.
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