OVER-THE-COUNTER MELATONIN: HOW IT WORKS, USES, MYTHS, AND MORE

Medically Reviewed by Dr. Rae Osborn, Ph.D. - September 27, 2024

Sleep is vital for health and well-being. However, many people struggle to get adequate quality sleep every night. According to the World Health Organization, an estimated one-third of the world’s population suffers from some form of sleep disorder, such as insomnia, sleep apnea, or restless legs syndrome. Prolonged sleep deprivation and similar problems can adversely impact physical and mental health, as well as increase the risk of cardiovascular disease, diabetes, obesity, depression, and cognitive impairment.

One of the factors that affect sleep quality is melatonin, also often referred to as the ‘sleep hormone’. Melatonin plays a key part in regulating our sleep-wake cycle or circadian rhythm. The body produces more melatonin after sunset, and this eventually signals when it’s time to fall asleep. Adequate melatonin levels promote longer and more restful sleep. Some may have low melatonin levels for various reasons, such as stress, jet lag, shift work, or exposure to artificial light at night. Melatonin production also slows down during aging, with lower melatonin levels being present in the elderly. This can disrupt sleep patterns and make it harder to get quality rest.

Fortunately, over-the-counter melatonin supplements are safe and effective for increasing melatonin levels and improving sleep quality in those who need them. In this article, we explore how melatonin works, its benefits and side effects, how to use it safely and effectively, and how it compares to other sleep medications. We will also address some common misconceptions and myths about melatonin.

What Is Melatonin?

Melatonin is a hormone produced by a small organ in the brain called the pineal gland. It is synthesized from serotonin, which is produced from^[1] the amino acid tryptophan and released into the bloodstream in response to darkness. Melatonin’s main function is to regulate the sleep-wake cycle by signaling to the body when it is time to sleep or wake up. It does this by binding to specific receptors in the brain and other organs that control various biological processes related to sleep and arousal.^[2]

Melatonin as an Antioxidant. In recent years, the majority of melatonin (>95%) has been shown to be produced in the mitochondria of all other cell types and has many other functions that are still being investigated.^[3] Melatonin is currently viewed as a master antioxidant, as it seems to play a vital role in regulating free radicals generated in the mitochondria. It also appears to be crucial for optimal glucose metabolism and for protecting the biliary tree from damage caused by bile acids.^[4] Research suggests that melatonin may be a lot more important to our physical functioning than previously believed, and it is currently being investigated for its efficacy as a complementary supplement for those with chronic lifestyle diseases.

Melatonin supplements are derived from either synthetic or natural sources. Synthetic melatonin is made in a laboratory and has the same chemical structure as the natural hormone. Natural melatonin is extracted from animal or plant sources. Both types of melatonin are available in different forms and dosages, such as tablets, capsules, liquids, sprays, or gummies. They can also be bought as immediate-release or slow-release products.

Food Sources of Melatonin: Additionally, melatonin can be found throughout the diet yet is especially rich in the following foods^[5]:

• Pistachios (the highest dietary source), walnuts and other nuts
• Black and red rice
• Cranberries, sour cherries, and other dark-colored berries
• Mustard seeds, fenugreek, cardamon, fennel, sunflower, black pepper and many other seeds and spices
• Lentil sprouts
• Kidney beans
• Eggs
• Fish
• St. John’s wort, feverfew, and other medicinal herbs

How Does Melatonin Work?

Melatonin supplements work by increasing blood concentrations of the hormone and enhancing its effects on the body. They promote sleep by:

• Reducing the time it takes to fall asleep (sleep latency)
• Increasing the duration of sleep (sleep efficiency)
• Improving the quality of sleep (sleep architecture)

As an increase in blood melatonin is a cue for sleep, and supplementation helps to adjust the circadian rhythm by shifting the phase of sleep onset and offset. This can be useful for people who have jet lag, shift work disorder, or delayed sleep phase syndrome by providing the right signal at the right time.

Research further suggests that melatonin’s antioxidant actions could also promote better sleep by lowering inflammation and other factors that can impact the quality of sleep and increase wakefulness at the wrong time. Antioxidants can help reduce inflammation related to stress, thereby increasing sleep quality.^[6]

Melatonin’s influence on sleep quality and duration depends on several factors, such as the dose, timing, individual variability, and the underlying sleep disorder. There is no general consensus on what dose works best for melatonin, although it is common knowledge that taking it 30-60 mins before bedtime is best for improving sleep quality and quantity. Taking it earlier in the day (not at repeat intervals) can cause the body to become tired sooner, which can help those deal with jetlag.

Is Melatonin Safe? Side Effects and Contraindications

Melatonin is generally considered safe and well-tolerated, with no adverse effects reported after decades of testing and minimal side effects that only affect some who use it.

Of those affected, common side effects of melatonin include:

• Daytime drowsiness and related symptoms, such as tiredness, grogginess, and subdued mood^[7]
• Headaches
• Dizziness
• Nausea
• Vivid dreams

These side effects are usually mild and transient, disappearing within a few days of adjusting to one’s dose. They also appear to be more common for melatonin agonists, which are other substances that mimic the actions of melatonin^[8]. If persistent, they can be reduced by lowering the dose, changing the timing of melatonin intake, or by taking it with food to promote slower release (up to 3 hours for peak effects).

Long-term use of melatonin has been documented as safe, even for just over 7 years, and on variable doses. There is no evidence to support any negative long-term side effects of melatonin or that it is addictive.

What Medications Should Not Be Taken With Melatonin?

Melatonin might be contraindicated for some people who are on certain prescription medications. As a potent antioxidant, it may interfere with how some medications are metabolized and may promote or increase their side effects or diminish their benefits as a result.

Liver metabolism of melatonin uses CYP1A2, CYP2C9 and CYP2C19 enzymes^[9]. If you are taking medications that are selectively metabolized using these enzymes, it may cause either melatonin or the medication to become less effective.

If you are on one or more prescription medications, such as calcium channel blockers^[10], melatonin supplementation may induce some of the following symptoms:

• Allergic reactions
• Hormonal imbalances
• Blood pressure changes
• Blood sugar changes
• Liver problems
• Seizures

Melatonin may also increase symptoms of drowsiness induced by sedatives, including benzodiazepines and anticholinergic medication.

It is important to consult a doctor about taking melatonin if you are on a long-term prescription. It may be best, as well, to begin with a low dose and carefully increase it until you are able to sleep well at night without side effects. If you experience any severe side effects, stop immediately and consult your doctor about other options.

Melatonin vs. Other Sleep Medications

Melatonin is often compared to other insomnia medications, such as prescription sleep meds (e.g., benzodiazepines) or over-the-counter antihistamines that promote better sleep (e.g., antihistamines, diphenhydramine, doxylamine). While melatonin exhibits similar effects, its mechanism of action differs from these medications, giving rise to unique advantages and disadvantages.

Melatonin benefits include:

• It is non-addictive and does not cause dependence or withdrawal symptoms
• At the right dose and timing, it does not impair cognitive or psychomotor performance or cause daytime sleepiness
• Fewer and milder side effects than most sleep drugs
• Many additional health benefits beyond sleep, such as antioxidant, anti-inflammatory, and neuroprotective properties

Some of the drawbacks of melatonin are:

• It is unregulated, and supplemental formulas may have variable quality, purity, and potency
• It may not be effective for everyone or for every type of sleep disorder
• It may interact with other medications or supplements that affect the central nervous system, such as antidepressants, anticonvulsants, opioids, or herbal remedies
• It may have unknown long-term effects on the body and the brain, although none have been reported even after 7 years of high-dose supplementation

Compared to other sleep medications, melatonin is safe and well-tolerated. If on other medications, it might be best to consult with your doctor to make sure it’s not contraindicated and to stick to a recommended dose. Under normal circumstances, it is advisable to start with a low dose and increase it gradually to arrive at an optimal dosage.

How Much Melatonin Should I Take? Dosage and Timing

The appropriate melatonin dosage and timing^[11] depend on several factors, such as your age, weight, health condition, sleep issue, and personal response. There is no universal or standard dose of melatonin, nor is there a way to assess melatonin overdose.

Here are some general guidelines that can help you find an optimal dose:

• Start with a low dose (2-5 mg) and gradually increase it until you find the effective dose for you.
• 10 mg is the maximum recommended dose;Take melatonin 30 minutes to 2 hours before your desired bedtime.
• Adjust the timing according to your circadian rhythm and your travel plans.
• Experiment with different forms and formulations of melatonin to see what works best for you.

You should also monitor your response to melatonin and keep track of any changes in your sleep quality, duration, or patterns. You may need to adjust your dose or timing accordingly or stop taking melatonin.

Bioavailability

Melatonin formulations are unstandardized, and the amount that is absorbed into the bloodstream depends on the form you take it in. The amount you absorb can vary between 1 and 74%, although it can still be potentially beneficial for the gut as well. Furthermore, some supplements may contain precursors and other factors that can boost melatonin synthesis, resulting in higher levels. This is another reason why melatonin’s effects may vary from person to person and why some may require higher doses than others for optimal sleep.

How long does it take for melatonin to work? Immediate-release melatonin can take 30-60 mins to work. Slow-release melatonin may take several hours to reach its peak, although some effects may be felt after 30 mins. Liquid melatonin may act faster than tablets as well.

How long does melatonin stay in your system? How long melatonin lasts depends on the form and dose. Oral melatonin is rapidly metabolized and excreted, with an absorption half-life of 6 mins and an elimination half-life of 54 mins. ^[12]Slow-release preparations may have a half-life of up to 2 hours. Melatonin is completely clear of the system 4-8 hours after ingestion^[13], although age and other factors may speed up or slow down its elimination.

Melatonin for Jetlag

It may help to supplement melatonin for combating jetlag, especially if crossing 5 or more timezones. Take your bedtime dose at the time you would be asleep at your destination on the day of travel. If traveling across 7 or more time zones, you may want to do this for 1-3 days in advance of travel.^[14] Once you arrive, you can also take melatonin 2-5 hours before your desired bedtime to trick your circadian clock into sleeping earlier (phase shift) or take it in the morning if you want your clock to adjust to a later-than-usual bedtime (phase delay).

Melatonin for Different Age Groups

Melatonin is active at all ages and may even be involved in the aging process.

Children under the age of 3 have the highest blood levels of melatonin, after which they are known to decline by as much as 80% throughout childhood^[15]. Following this, they continue to decline at a slower pace, which may be yet another reason sleep issues and inflammation increase with aging. Some studies reveal that in people in their 90s^[16], blood melatonin levels can drop to as low as 20% of what they were while they were young adults.

As children have naturally higher levels, they don’t need as much for improving sleep, whereas older adults, the elderly, and those with health conditions may benefit from much more.

Melatonin for Children

Children can battle to fall asleep for a number of reasons, with some of the most common ones pertaining to nightmares, excitement before bed, or developmental disorders such as autism. Sleep disorders and occasional sleep issues have been successfully treated with melatonin supplementation with little to no side effects. Melatonin can help children drift off faster and sleep longer, which can improve their mood, behavior, learning abilities, and lower the risk of acquiring a sleep disorder later in life^[17].

The recommended dose of melatonin for children ranges from about 1 to 6 mg based on the child’s age, weight, and sleep problem. Melatonin should be taken 30 minutes to 1 hour before bedtime. It is most often used occasionally or for a few nights to correct the circadian rhythm, yet those with autism or chronic sleep disorders may benefit from long-term use.

Melatonin for the Elderly

Aside from having lower body melatonin, the elderly may experience changes in their sleep patterns because of aging, medical conditions, medications, or lifestyle factors. They may have difficulty falling asleep, staying asleep, or waking up too early.

Melatonin can help the elderly restore their natural sleep cycle, improving sleep quality and duration^[18]. It can also have other benefits, such as enhancing their cognitive function, mood, immune system, and cardiovascular health^[19].

While seemingly promising for reversing some age-related effects, supplementation may come with drawbacks. Melatonin’s side effects in elderly individuals include interference with multiple medications, leading to unintended effects, as well as promoting increased drowsiness or dizziness, which may contribute towards the risk of falls and injuries.

Therefore, melatonin use in the elderly should be done with care, ensuring that the individual’s doctor is kept informed of any changes that occur.

Melatonin Benefits Beyond Sleep

Melatonin is not only a sleep hormone. It also has other functions and benefits that go beyond sleep regulation. Some other benefits of melatonin include:

• Improving mood by combating anxiety and stress^[20]. Melatonin can aid in reducing anxiety and stress levels by helping to regulate the activity of neurotransmitters and stress hormones such as serotonin, dopamine and cortisol. This helps to maintain a stable mood and prevent mood swings.
• Reducing blood pressure and boosting heart health^[21]. Melatonin can help lower blood pressure and improve heart health by relaxing blood vessels and reducing inflammation.
• Protecting against oxidative stress and inflammation^[22]. As a powerful antioxidant, melatonin is used by the mitochondria to scavenge free radicals and protect cells from inflammatory damage. Melatonin also reduces inflammation by directly inhibiting pro-inflammatory cytokines^[23].
• Supporting immune system function^[24]. The immune system benefits from melatonin, which increases the production of natural killer cells, T cells, B cells, and antibodies. It also helps to regulate the expression of inflammation, which helps to temper allergic reactions and other immune responses. Melatonin may also be an important part of breast milk that contributes towards infantile immunity.
• Improving certain disease parameters^[25]. Research is currently investigating melatonin’s potential benefits in preventing or treating some diseases that are related to oxidative stress, inflammation, or circadian disruption. These include Alzheimer’s disease, Parkinson’s disease, cancer, diabetes, obesity, migraine, irritable bowel syndrome (IBS), and more.

Melatonin may additionally be of benefit to bone, reproductive tissues, digestion, mental health, and regulating body composition.

Addressing Common Misconceptions

Despite its popularity and widespread use, melatonin is still surrounded by myths and misconceptions that need to be clarified. Some of these include:

Myth 1: Melatonin causes Headaches, Diarrhea, or Anxiety.

These are not common side effects of melatonin use. In fact, melatonin may help prevent or reduce these symptoms by improving sleep quality, reducing inflammation, or regulating serotonin levels. Side effects include headaches, daytime drowsiness, and dizziness, and are more common when taking high doses^[26]. Side effects tend to resolve after an adjustment period.

Myth 2: Long-term Melatonin Use can cause Developmental Problems in Kids.

Some sources explain that melatonin might cause problems with growth and hormones in children if supplemented long-term. There is no evidence of any adverse events occurring in children who have used melatonin every night for several years, not even after 10 years of use.^[27]

Myth 3: Melatonin leads to Tolerance or Dependency.

Melatonin is not addictive. While its initial use was tempered in case of withdrawal or dependency, similar to other sleeping meds, there has never been any evidence to support that melatonin causes tolerance or dependency. Melatonin is used and excreted at a rapid rate by all cells and is more than just a circadian hormone.

Myth 4: Melatonin Withdrawal causes Symptoms such as Rebound Insomnia.

Some sources cite that melatonin withdrawal can cause rebound insomnia, which is a temporary worsening of sleep quality or quantity after stopping melatonin or after taking “too high a dose”. Many of these sources reference literature pertaining to other sleeping meds, such as benzodiazepines, which have an entirely different mechanism of action compared to melatonin.

Rebound insomnia is not a well-documented occurrence in those taking or stopping melatonin supplementation. There is very little evidence to support that it induces other symptoms of withdrawal, such as headaches or fatigue, and in these rare cases, these are likely related to underlying health conditions.

Myth 5: Melatonin is a Magic Pill that can Solve all your Sleep Problems.

Melatonin is not a cure-all for sleep issues. It can help improve your sleep quality and quantity, but it cannot address the root causes of your sleep problems. Melatonin should be used as a supportive supplement, not a substitute, for good sleep hygiene and healthy lifestyle habits, such as:

• Keeping a regular sleep schedule and avoiding naps.
• Avoiding caffeine, alcohol, nicotine, and heavy meals close to bedtime.
• Limiting exposure to blue light and artificial light at night.
• Creating a comfortable and dark sleeping environment.
• Engaging in relaxing activities before bed, such as reading, listening to music, or meditating.
• Exercising regularly and avoiding strenuous activities before bed.
• Managing stress and anxiety levels.
• Seeking professional help for any medical or psychological conditions that may affect your sleep.

Conclusion

A natural hormone and antioxidant, melatonin can help you sleep better by regulating your circadian rhythm and enhancing sleep quality and duration. Supplemental melatonin may have other benefits for your health and well-being, such as enhancing glucose metabolism, reducing anxiety, lowering blood pressure and inflammation, boosting immune function, and improving cognition.

Melatonin is generally safe and effective with little to no side effects, most of which are tolerable and temporary. While effective for many, it is not a replacement for good sleep hygiene, which includes getting to bed on time, relaxing before bed, and limiting bright light, as well as leading a healthy lifestyle in general.

If you are interested in trying over-the-counter melatonin for better sleep, you might want to pay attention to the quality, potency, purity, and labeling of products, as they are not currently regulated. It might take some time to see what melatonin supplement works best for you and to find the right dose. Prior to starting any supplement, it is best to consult your doctor for personalized advice.

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