Get Your Personalized Supplement StackSupplement Stack Quiz

Melatonina

Also known as: N-acetyl-5-methoxytryptamine, Melatonina, Melatonin

Overview

Melatonin is a hormone primarily produced by the pineal gland in the brain, playing a crucial role in regulating the body's circadian rhythms and sleep-wake cycles. It is also found in trace amounts in certain foods and is widely available as an exogenous supplement. Melatonin supplements are predominantly utilized to enhance sleep quality, address sleep disturbances such as insomnia and jet lag, and normalize disrupted circadian rhythms. This lipophilic hormone readily crosses the blood-brain barrier and exerts its effects by interacting with specific melatonin receptors (MT1 and MT2) to influence sleep regulation. Extensive research, including numerous randomized controlled trials, systematic reviews, and meta-analyses, supports its efficacy in improving various sleep parameters, with high-quality evidence indicating its role as a valuable sleep aid.

Benefits

Melatonin offers several evidence-based benefits, primarily centered around sleep improvement. It significantly reduces sleep onset latency by approximately 7 minutes and increases total sleep time by about 8 minutes compared to placebo, as demonstrated in meta-analyses of randomized controlled trials. These effects, while modest, are statistically significant and contribute to improved sleep efficiency. Furthermore, melatonin has been shown to enhance overall sleep quality, with a small to moderate effect size. Adults experiencing primary sleep disorders are the most clear beneficiaries. While some preliminary evidence suggests potential benefits on metabolic parameters like fasting blood glucose and insulin resistance in diabetic populations, this area requires more robust confirmation. The efficacy of melatonin in improving sleep parameters appears to correlate with longer duration of supplementation and higher doses.

How it works

Melatonin primarily exerts its effects by acting on MT1 and MT2 receptors located in the suprachiasmatic nucleus (SCN) of the hypothalamus. This interaction is crucial for regulating circadian rhythms and promoting the onset of sleep. By modulating the sleep-wake cycle within the central nervous system, melatonin helps to synchronize the body's internal clock with the external environment. Beyond its role in sleep, melatonin also possesses antioxidant properties. When taken orally, melatonin is rapidly absorbed, with peak plasma concentrations typically occurring within 30-60 minutes, though its bioavailability can vary due to first-pass metabolism.

Side effects

Melatonin is generally considered safe and well-tolerated in adults. Common side effects, occurring in more than 5% of users, are typically mild and include headache, dizziness, and daytime sleepiness. Less common side effects, affecting 1-5% of individuals, may include nausea and irritability. Rare side effects, occurring in less than 1% of users, can involve hormonal effects, such as changes in reproductive hormones. Melatonin has potential interactions with several medications, including anticoagulants (increasing bleeding risk), immunosuppressants, diabetes medications (potentially affecting blood sugar control), and sedatives (enhancing their effects). Caution is advised for pregnant or breastfeeding women due to limited safety data, and for individuals with autoimmune diseases. While generally safe, long-term use and safety in children require further dedicated study, though higher doses up to 10 mg have been systematically reviewed and found safe in adults.

Dosage

For improving sleep onset, a minimum effective dose of 0.5 to 1 mg of melatonin is typically recommended. Optimal dosage ranges commonly fall between 1 to 5 mg, although higher doses up to 10 mg have been safely studied in adults. A systematic review suggests that doses up to 10 mg are safe for adult use. Melatonin is best taken approximately 30 to 60 minutes before bedtime to allow for absorption and onset of action. Immediate-release formulations are generally preferred for addressing sleep onset difficulties, while extended-release formulations may be considered for maintaining sleep throughout the night. The bioavailability of oral melatonin can be influenced by food intake and the specific formulation used. No specific cofactors are required for its efficacy.

FAQs

Is melatonin safe for long-term use?

Current evidence supports the safety of melatonin in adults for up to several months. While long-term safety data are limited, no major concerns have been reported regarding its extended use.

When should melatonin be taken?

For optimal effect, melatonin should be taken approximately 30-60 minutes before your desired bedtime. This allows sufficient time for absorption and the hormone to begin influencing sleep onset.

How quickly does melatonin work?

Effects on sleep onset can typically be observed within days of starting melatonin supplementation. Its action is relatively rapid once absorbed into the bloodstream.

Does melatonin cause dependence?

There is no evidence to suggest that melatonin causes dependence or withdrawal symptoms, making it a non-addictive option for sleep support.

Can melatonin help with jet lag?

Yes, melatonin is effective in helping to adjust circadian rhythms, which can be beneficial for alleviating the symptoms of jet lag, though this was not the primary focus of the cited meta-analyses.

Research Sources

https://pubmed.ncbi.nlm.nih.gov/33417003/ – This systematic review and meta-analysis of RCTs found that melatonin significantly improves sleep quality, as measured by the Pittsburgh Sleep Quality Index (PSQI), in adults with sleep disorders. The study highlighted melatonin's positive impact on subjective sleep parameters, despite heterogeneity in doses and populations across included studies.
https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0063773 – This meta-analysis of 19 RCTs involving 1683 subjects with primary sleep disorders concluded that melatonin significantly reduced sleep latency by approximately 7 minutes and increased total sleep time by about 8 minutes. It also improved overall sleep quality, though the effect sizes were modest, indicating melatonin's efficacy as a sleep aid.
https://onlinelibrary.wiley.com/doi/10.1111/jpi.12782 – This systematic review and meta-analysis specifically focused on the safety profile of melatonin at higher doses (up to 10 mg) in adults from various RCTs. The findings indicated that melatonin is generally safe and well-tolerated at these doses, with mild and transient side effects, although long-term safety data remain limited.