How Melatonin Regulates Sleep, Circadian Rhythms, and Well-being
Introduction:
Melatonin is a hormone mainly produced by the pineal gland that controls the sleep – wake cycle. As a dietary supplement, it is often used for the short - term treatment of depression, such as from jet lag or shift work, and is usually taken by mouth. Proof of its utility for this use, however, is not good.
Melatonin was discovered in 1958. It is sold over the counter in Canada and the United States; in the United Kingdom, it is a prescription-only medication. It is not approved by the US Food and Drug Administration (FDA) for any medical use. In Australia and the European Union, it is indicated for difficulty sleeping in people over the age of 54. In the European Union, it is indicated for the treatment of insomnia in children and adolescents. It was approved for medical use in the European Union in 2007.
Melatonin Hormone Functions:
Circadian Rhythm
Melatonin plays an important role in sleep regulation-wake cycles in animals. The level of melatonin in human infants becomes regular in about the third month after birth, with the highest levels measured between midnight and 8 am. Human production of melatonin decreases as a personages. Also, as children become adolescents, the melatonin release schedule for the night is delayed, leading to later sleeping and waking times.
Antioxidant
Among animals, melatonin plays an important role in the regulation of sleep – wake cycles. Human infants ' melatonin levels are normal in about the third month after birth, with the highest levels recorded between midnight and 8:00 am. Human melatonin output declines as a person ages. Also, when children become adults, the nightly cycle of melatonin release becomes postponed, leading to later sleeping and waking hours.
Immune System
While it is understood that melatonin interacts with the immune system, the specifics of those interactions remain unknown. The anti - inflammatory effect seems to be the most important. There were few studies designed to assess the efficacy of melatonin in the treatment of diseases.
Medical Uses:
Positions on the effects of melatonin for insomnia are mixed. An Agency for Healthcare Research and Quality (AHRQ) study from 2015 reported that proof of gain in the general population was uncertain. A study from 2017, found a modest effect on time before the onset of sleep. Another study from 2017 placed this decrease at six minutes to sleep onset but reported no correlation in total sleep time. Melatonin may also be useful in delayed sleep phase syndrome. Melatonin tends to function as well as ramelteon but costs less.
Dementia
A 2016 Cochrane review found no evidence that melatonin helped sleep problems in people with moderate to severe dementia due to Alzheimer's disease. A 2019 review found that while melatonin could improve sleep with minimal cognitive impairment, it has little to no effect after Alzheimer's onset. However, melatonin can aid to sunset.
Jet Lag and Shift Work
Melatonin is known to reduce the jet lag, especially when traveling eastward. However, if the time it is taken isn't correct, it may delay adaptation instead. Native evidence suggests the length of time people can sleep increases.
Occurrence:
As a Dietary Supplement:
Melatonin is categorized by the US Food and Drug Administration (FDA) as a dietary supplement.
Food Products:
Melatonin is categorized by the US Food and Drug Administration (FDA) as a dietary supplement.
Adverse Effects:
Naturally-occurring melatonin has been reported in foods including tart cherries to about 0.17–13.46 ng/g, bananas and grapes, rice and cereals, herbs, plums, olive oil, wine and beer.
Melatonin can lower levels of the hormone that stimulates follicles. The effects of Melatonin on human reproduction remain unclear.
In those taking warfarin, some evidence suggests there may exist a potentiating drug interaction, increasing the anticoagulant effect of warfarin and the risk of bleeding.
FAQs on Melatonin Hormone: Key Functions and Health Benefits
1. What is melatonin and which gland in the human body secretes it?
Melatonin is a hormone primarily responsible for regulating the body's sleep-wake cycles. It is secreted by the pineal gland, a small endocrine gland located in the epithalamus, near the centre of the brain. Its production is stimulated by darkness and suppressed by light.
2. What is the main biological function of the melatonin hormone?
The primary function of melatonin is the regulation of the 24-hour diurnal rhythm of our body. It helps maintain the normal sleep-wake cycle by signalling to the body when it is time to sleep. This process is crucial for maintaining overall health and the timing of various physiological processes.
3. How does light exposure influence the production of melatonin?
Melatonin production is inversely related to light exposure. The suprachiasmatic nucleus (SCN) in the brain, often called the master clock, receives signals about light from the retina. In darkness, the SCN signals the pineal gland to produce and release melatonin. When exposed to light, this signal is inhibited, and melatonin production decreases significantly.
4. Why is melatonin often referred to as the 'hormone of darkness'?
This term is used because melatonin levels in the bloodstream are highest during the night and lowest during the day. Its synthesis and release are stimulated by darkness and inhibited by light. This nightly peak is the body's biochemical signal for night, which is why it plays a fundamental role in initiating and maintaining sleep.
5. Beyond regulating sleep, what are some other important functions of melatonin?
In addition to its primary role in the sleep-wake cycle, melatonin also performs several other vital functions. These include:
- Influencing metabolism: It plays a role in regulating energy balance and body weight.
- Supporting the immune system: It helps modulate the body's defence mechanisms.
- Acting as an antioxidant: It helps protect cells from oxidative stress and damage from free radicals.
- Regulating reproduction: It can influence the timing of puberty and reproductive cycles by affecting gonadotropin-releasing hormones.
6. What are the potential consequences of a melatonin imbalance in the body?
An imbalance in the body's natural melatonin production can disrupt physiological functions. Hyposecretion (low levels) can lead to insomnia, poor sleep quality, anxiety, and a misaligned circadian rhythm. Conversely, hypersecretion (abnormally high levels) can cause daytime sleepiness, lethargy, and may interfere with the normal functioning of the reproductive system.
7. How does melatonin's function in humans differ from its role in other animals?
While melatonin regulates the sleep-wake cycle in humans, its role can be more extensive in other animals. For instance, in many seasonal breeding animals, the duration of nightly melatonin secretion provides information about the length of the day. This helps them time their reproductive cycles, migration, and hibernation to coincide with the most favourable seasons of the year. It also has a more pronounced effect on pigmentation (skin colour) in lower vertebrates like amphibians.
