What is melatonin and what are its benefits?

What is melatonin and what are its benefits?

Publication date: 14-03-2024

Updated on: 15-03-2024

Topic: Neurology

Estimated reading time: 1 min

Melatonin is a hormone that regulates our sleep and is produced almost exclusively by the pineal gland or epiphysis, a structure located deep in the brain. Levels of melatonin in the blood vary over the 24 hours: in particular, they are low during the day while they begin to rise about 1 to 3 hours before the usual time at which one goes to bed, remain high throughout the duration of sleep, and decline about an hour before the time of awakening.

It performs many functions and is used both to normalize sleep and to treat other ailments, such as insomnia. 

Dr. Paola Proserpio, an expert neurologist in sleep disorders at the Neurology Operating Unit at IRCCS Ospedale San Raffaele Turro, explains what mechanisms regulate the function of this hormone, what its effects are, and how it is used.

Melatonin and circadian rhythm

"As anticipated, melatonin has several activities but, as far as sleep is concerned," Dr. Proserpio explains, "it represents the main hormone that regulates the circadian rhythm, that is, the mechanism that allows synchronization between: 

  • light/dark rhythm;
  • sleep/wake rhythm. 

Basically, the reduction of light stimulation in the evening hours activates, through particular receptors in the retina, the production of melatonin by the pineal gland. Through reducing internal temperature levels, this substance, in turn, activates sleep-inducing mechanisms.

Based on the time at which melatonin is produced, 2 types, or chronotypes, of subjects are distinguished: 

  • “Owls”, i.e., people with a serotype chronotype, are individuals who tend to be very active and high-performing in the evenings, go to bed late, but then have difficulty waking up early in the morning;
  • “larks,” or morning chronotype, are those people who experience drowsiness early in the evening, but then manage to get up early in the morning and be more productive in the early hours of the day."

When supplementation may be useful

As melatonin is the main hormone that regulates circadian rhythm, its supplementation may have utility:

  • in inducing sleep (especially in the elderly);
  • in regulating the sleep-wake rhythm. 

"Unfortunately, levels of endogenous melatonin (i.e., which is produced internally) decline dramatically with age, and this may be one of the factors behind the reduction in sleep quality and quantity in adult-elderly subjects. Therefore, the use of extended-release melatonin is recognized as a treatment option for insomnia in individuals after age 55," the specialist continues.

Conversely, since melatonin also regulates the time at which the subject falls asleep, its use appears to be indicated in individuals with circadian rhythm disorder. 

As an example, in modern reality, adolescents often tend to increasingly postpone their bedtime, sometimes struggling to wake up at a convenient time to be able to go to school. If this problem becomes chronic and worsens over time, it can greatly interfere with daytime performance and the subject's ability to wake up and stay awake and alert in school (this is referred to as “phase postponement syndrome”). In these situations, the consistent use of melatonin a few hours before falling asleep, along with behavioral rules, can be a useful tool to solve the issue.

Finally, the use of melatonin has been recently recognized as one of the first-choice treatments in children/adolescents with neurodevelopmental disorders (particularly autism) and sleep disorders."

How to take melatonin: indications and side effects

There are numerous melatonin formulations on the market, both ready- and slow-release, often in combination with other phytotherapeutic substances. As a drug, only extended-release melatonin (2 mg) indicated in the treatment of insomnia in individuals older than 55 years is recognized. 

"For the treatment of circadian rhythm disorders," says the specialist, "ready-release formulations are suggested instead, even at lower dosages (1 mg). 

Unfortunately, current guidelines show us that there are no solid studies to date in favor of the efficacy of phytotherapeutics (e.g., magnesium, tryptophan, valerian, chamomile) in the treatment of insomnia. There is, however, limited evidence to suggest the usefulness of these substances in some cases of insomnia, especially considering the fact that they appear to be free of contraindications and side effects."

The only side effect of melatonin is excessive sedation, a sensation that may be present especially in the morning upon awakening and tends to diminish over the course of the day. This rarely occurs in hypersensitive individuals and, especially, in the elderly. 

Caution should also be observed in people with autoimmune diseases. Finally, considering that there are no efficacy and safety studies, its use is contraindicated in pregnancy.

Other uses related to melatonin

"More and more studies show that melatonin is a substance with multiple regulatory actions in our body's systems," Dr. Proserpio concludes. – "For example, it is recognized to have anti-inflammatory and antioxidant action, so its use was recommended during the Covid-19 pandemic to reduce the susceptibility or severity of the disease.

Moreover, through its anti-inflammatory and neuroprotective action at the level of the central nervous system, it appears that this hormone may have a protective action against neurodegenerative diseases by preventing, in particular, the deposition and accumulation of neurotoxic substances. 

Other evidence, yet to be confirmed with clinical studies in large populations, suggests its potential role and use: 

  • in modulation of pain;
  • in improving fertility;
  • in reducing the progress of oncological diseases;
  • in improving the course of chronic psychiatric diseases."

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