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The dark side of melatonin for sleep - is it really safe?

22 lipca 2022

Melatonin for sleep, sleep tablets, natural methods to fall asleep, sleep medication, melatonin overdose

Contents

How does melatonin affect sleep?

What are the side effects of melatonin?

Can melatonin be overdosed?

How does melatonin impact the hormonal system?

Who can take melatonin for sleep and when?

What else helps with sleep besides melatonin?

It's hard not to notice that falling asleep difficulties are affecting more and more people - which is why supplements sold as melatonin for sleep are becoming increasingly popular. You can buy them over the counter in pharmacies and online stores, and manufacturers often promote them as a natural and completely safe way to treat insomnia - even though they don’t address the root causes. It’s important to remember that melatonin is not a vitamin or a herb, but a hormone that regulates our circadian rhythm. That’s why taking melatonin for sleep can have serious consequences.

The first enthusiastic reports about the effectiveness of melatonin for sleep appeared in 1994, when scientists from the Massachusetts Institute of Technology (MIT) published research findings suggesting that small doses of the hormone can shorten the time it takes to fall asleep. Volunteers in the melatonin sleep study were divided into two groups - one test group and one control group. The test group received small doses of melatonin before bed, while the control group was given a placebo. The results showed that people taking melatonin for sleep fell asleep three times faster.

The scientific community and the media hailed melatonin as a potential breakthrough in the fight against insomnia. Unfortunately, they quickly forgot that every hormone carries a risk of disrupting bodily functions - and that self-administering melatonin isn’t always justified.

Although melatonin for sleep was soon marketed as an alternative to traditional sleeping pills, experts immediately pointed out that melatonin supplementation should mainly apply to older people, whose natural hormone production in the pineal gland decreases with age. In younger patients, unjustified use of melatonin for sleep may lead to overdosing - though this is rare. It may also cause hormonal imbalance or even worsen sleep issues.

Just a few years after the above study was published, Professor Richard Wurtman, a leading neuroscientist from the same university, warned against the rash use of melatonin as a dietary supplement. He emphasized that a lack of medical supervision over melatonin dosage, along with quality inconsistencies in over-the-counter products, could pose real risks. It was also pointed out that melatonin for sleep should not be used in children without explicit medical guidance - even if it’s claimed to be the best melatonin on the market.

Melatonin, sleep tablets, sleep medication, can melatonin be overdosed?

How does melatonin affect sleep?

It’s important to remember that melatonin is not a vitamin or herb, but a hormone naturally produced in the human body. Its main source is the pineal gland - a small gland whose activity depends on the light-dark cycle. Small amounts of melatonin are also produced by cells in the retina and gastrointestinal tract. This is why melatonin plays a crucial role in regulating the body’s circadian rhythm and sleep quality.

One of the most important functions of melatonin is to signal the brain that it’s time to rest. As night falls, the melatonin level in the body rises - and decreases in the presence of light. That’s why sleep hygiene is key. Production of this hormone is supported by avoiding blue light a few hours before bedtime and by darkening the room.

As described in scientific literature, melatonin is a rhythmic hormone. It works best when released or taken at the right time, helping to prevent shifts in the body’s biological clock. Studies show that melatonin supplementation at the wrong time of day may actually worsen sleep problems. Results in human studies also vary depending on dosage and timing - showing that melatonin is not a one-size-fits-all solution but requires individual adjustment.

Another scientific article indicates that melatonin acts as a night-time signal, as the hormone synchronizes the body’s internal clocks and coordinates circadian rhythms such as sleep-wake cycles, body temperature regulation, metabolism and immune response. The authors also point out that in pathological conditions, endogenous melatonin production can be severely impaired - negatively impacting health and sleep quality. Understanding these mechanisms is crucial for the proper use of melatonin in treating sleep disorders and other conditions.

Melatonin is not a herbal sleep pill, but a powerful hormone that affects the entire body. After entering the bloodstream, melatonin binds to MT1 and MT2 receptors in the suprachiasmatic nuclei (SCN) of the hypothalamus. This is where the biological clock is located - the part of the brain responsible for regulating the sleep-wake cycle. The highest melatonin concentrations occur at night, typically between 12:00 a.m. and 3:00 a.m., supporting deep sleep phases and physical regeneration.

Therefore, melatonin works as a sleep aid primarily by regulating the circadian rhythm - not as a traditional sleeping pill. Its main role is to support falling asleep by synchronizing the internal clock, not by inducing drowsiness. That’s why melatonin supplementation may be helpful in cases of disrupted sleep rhythms or in older age, when natural melatonin production generally declines. Otherwise - especially in healthy individuals - melatonin supplementation may do more harm than good.

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What are the side effects of melatonin?

As a general rule, taking synthetic hormones without medical supervision is never entirely safe. That’s because the human hormonal system is highly sensitive to changes - even small fluctuations in the level of a single hormone can affect the balance of the entire body. Therefore, melatonin for sleep, although perceived as natural and safe, is not without health implications. As noted in scientific literature, its side effects can be unpleasant. These include daytime drowsiness, headaches, dizziness, lowered body temperature and even gastrointestinal issues.

In the US, melatonin for sleep is registered as a dietary supplement, not a drug. This allows manufacturers to bypass the costly clinical trials required by the FDA for drug approval. As a result, quality control for melatonin supplements is limited. Studies have found that the actual contents and dosages often differ from what’s declared on the label, due to a lack of effective oversight. As reported in a scientific article, melatonin content in 30 tested supplements varied from -83% to +478% compared to label claims.

In Poland, the situation is different - melatonin for sleep is registered as an over-the-counter drug. This means locally produced products should, in theory, have a stable composition and accurate dosage, as they are subject to the same regulations as other pharmaceuticals. At the same time, the market also offers foreign melatonin preparations sold as dietary supplements.

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Can melatonin be overdosed?

Frequent use of melatonin for sleep without medical supervision is not recommended. It’s important to remember that melatonin overdose is possible and may be dangerous. Although this hormone naturally occurs in the body and helps regulate the circadian rhythm, taking too much of it in the form of melatonin tablets or capsules carries a risk of side effects.

Experts indicate that an effective melatonin dose for sleep is usually up to 1 mg per day. Melatonin should also be used short-term and preferably under medical supervision. However, products containing as much as 10 mg of melatonin per tablet are available on the market. Such high doses can lead to excessive drowsiness and concentration issues, and in some cases to hypothermia, since melatonin lowers body temperature. At the same time, clinical studies have shown that taking more melatonin does not help you fall asleep faster - it only increases the risk of side effects.

Melatonin for sleep? Not for everyone. It can be overdosed!

Scientific literature also describes clinical cases in which even a single intake of high doses of melatonin led to hospitalization due to severe drowsiness and a drop in body temperature. This shows that melatonin can be dangerous when used irresponsibly.

The most common symptoms of melatonin overdose for sleep include:

headaches;
dizziness;
gastrointestinal disturbances;
weakness and confusion;
excessive daytime sleepiness;
paradoxical worsening of sleep quality.

Let’s not forget that melatonin for sleep, just like any drug or supplement, should be used wisely. That means always in the lowest effective dose, and of course only when truly justified. In healthy individuals, melatonin supplementation is not recommended, as it may do more harm than good.

Melatonin, sleep tablets, natural methods to fall asleep, sleep medication

How does melatonin impact the hormonal system?

It’s often forgotten that the human hormonal system works like a precise network of interconnected vessels. Even a slight change in hormone levels can disrupt the balance of the entire system. This applies to melatonin for sleep as well – although naturally produced in the pineal gland, it acts as an exogenous hormone when taken as a supplement. Overuse of melatonin can affect cortisol – the stress hormone – and has also been linked to changes in growth and sex hormones, leading to noticeable effects on the body.

Experts note that melatonin can modulate the function of gonadotropins, including follicle-stimulating hormone (FSH) and luteinizing hormone (LH). In women, this may cause menstrual cycle disturbances, while in men it can affect testosterone levels. Some studies also suggest that long-term melatonin supplementation influences prolactin (PRL) levels, which play a role in reproductive health.

What’s more, taking melatonin supplements may reduce the body’s ability to produce it naturally. Consistent external intake can lead to desensitization of MT1 and MT2 receptors in the brain – reducing sensitivity to endogenous melatonin produced by the pineal gland. This can interfere with the natural circadian rhythm and ultimately lower sleep quality rather than improve it.

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Who can take melatonin for sleep and when?

Melatonin is most often used as a dietary supplement that may be beneficial in specific situations. It's important to understand that melatonin for sleep is not suitable for everyone. Its use should always follow a doctor’s recommendations, or guidance from another qualified healthcare professional with proper medical training and legal certification.

When used in appropriate doses, melatonin can be helpful for people working shifts, or those with neurodegenerative diseases like Alzheimer’s. It is also sometimes used as part of treatment for bipolar disorder. Before starting melatonin supplementation, you should always consult a specialist to assess both your personal needs and the potential risks of taking this hormone.

If taken under medical supervision and in the right dose, melatonin for sleep can indeed help treat insomnia – but primarily in older adults and people with conditions such as multiple sclerosis (MS). It is also commonly used in blind individuals, as recent scientific studies have shown melatonin helps maintain a proper sleep-wake rhythm throughout the day.

Melatonin may support falling asleep, but using it long-term and unsupervised can backfire. When there’s too much melatonin in the body, the brain becomes desensitized. Receptors stop responding well – and both the supplement and the melatonin produced naturally become less effective. This is not candy – it’s a hormone in pill form that, in high doses, can disrupt your natural sleep cycle.

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What else helps with sleep besides melatonin?

Not every sleep issue requires taking melatonin – in many cases, simply improving your sleep hygiene by adjusting daily habits can be enough. A consistent sleep-wake rhythm – going to bed and waking up at the same time every day – is essential. This is confirmed by scientific studies on the role of routine in sleep quality. It’s also recommended to avoid naps in the afternoon or evening, as they can interfere with nighttime rest.

Natural methods for relaxation can also help. Ashwagandha, in particular, is gaining popularity for its calming and anti-anxiety effects. It's one of the most well-researched adaptogens. Scientific studies have shown that people taking ashwagandha fell asleep faster, had better sleep efficiency, and experienced improved sleep quality compared to a placebo group.

Bedroom conditions also play a major role – yet are often overlooked. The ideal temperature is below 20°C, and quiet and darkness are crucial to support natural melatonin release. Sleep comfort depends heavily on proper equipment – that means a comfortable mattress and an anatomical pillow. Sleep ergonomics research indicates that the ideal mattress firmness for most people is around 6.5 on the American scale – offering both support and comfort. That’s why ONSEN® created the Osaka Air mattress, which combines these features and guarantees lasting comfort – backed by a 15-year warranty.

It’s equally important to avoid factors that disrupt sleep, such as caffeine, alcohol, nicotine, or heavy meals before bed. Adding elements like mindfulness, evening reading, or light stretching to your routine can significantly improve your ability to fall asleep naturally. This helps you avoid the risks associated with overusing melatonin – and supports healthy sleep in a safe way.

We also encourage you to explore other articles on the best sleep and health blog, as well as the Encyclopedia of Healthy Sleep prepared by the ONSEN® team of specialists. For those who care about spine health, we recommend a set of spine exercises prepared by our physiotherapist.

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FAQ: Melatonin for sleep

Is it worth taking melatonin for sleep?

Yes, taking melatonin can be helpful - but only in specific cases. Melatonin may support falling asleep, especially in older adults whose natural production of the hormone is reduced. In such cases, supplementation can help regulate the sleep-wake cycle. For younger, healthy individuals, taking melatonin without medical advice is not recommended - it can lead to side effects or hormonal imbalance.

How many hours do you sleep after taking melatonin?

Melatonin does not significantly increase total sleep time. In general, people sleep the same amount as without it. Its primary effect is to shorten the time it takes to fall asleep. In studies, participants fell asleep after about 5 minutes with melatonin - compared to 15 minutes in the placebo group. So it helps you fall asleep faster, but the overall sleep duration depends on your individual needs.

What are the side effects of melatonin used for sleep?

Melatonin can cause certain side effects. Most notably, it may impair sleep quality and disrupt the hormonal system. At higher doses, it can lower body temperature (hypothermia). An overdose may also cause headaches, nausea, fatigue and excessive daytime drowsiness.

Can melatonin be overdosed?

Yes, it is possible to overdose on melatonin. Excessive doses can disrupt hormonal balance and lead to drowsiness, weakness, sleep disturbances and lowered body temperature (hypothermia). It is a hormone that affects the entire endocrine system.

Can melatonin be taken daily?

Daily use of melatonin is not recommended without clear medical guidance. Regular intake may cause the body to produce less of its own melatonin and reduce receptor sensitivity to the hormone.

Contents

How does melatonin affect sleep?

What are the side effects of melatonin?

Can melatonin be overdosed?

How does melatonin impact the hormonal system?

Who can take melatonin for sleep and when?

What else helps with sleep besides melatonin?

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Comments

Paweł write:

"Melatonina może rozregulować układ hormonalny". Proszę o podanie źródła tej informacji.

Added: 6 października 2023, 22:29. Add an answer

Mateusz Nesterok write:

Melatonina jest hormonem. Wszelkie odstępstwa od fizjologicznie występujących stężeń hormonów we krwi rozpatruje się jako zaburzenia hormonalne. Z zasady hormony działają tak, że jeśli ilość jednego się zmieni, to i stężenie pozostałych (wszystkich lub części) ulega zmianom. Melatonina dużych ilościach może u niektórych wywoływać niekorzystne a wśród nich nudności, zmęczenie czy stany depresyjne. Wpływać może, między innymi, na poziom serotoniny czy dopaminy. Stąd też melatonina w nadmiarze może - ale nie zawsze musi - prowadzić do rozregulowania całego układu hormonalnego.

Added: 7 października 2023, 09:39. Add an answer

ONSEN® Expert write:

Pawle, dziękujemy za uważną lekturę i trafne pytanie. W artykule powołujemy się - między innymi - na publikacje naukowe dostępne w bazach PubMed i NCBI, które wskazują, że długotrwałe przyjmowanie melatoniny w wysokich dawkach może wpływać na gospodarkę hormonalną. Na przykład przez oddziaływanie na oś podwzgórze?przysadka?gonady. Chętnie prześlemy Ci linki do badań, jeśli jesteś zainteresowany szczegółami.

Added: 23 września 2025, 09:41. Add an answer

Paweł write:

To nie jest odpowiedź na moje pytanie. Proszę przeczytać je jeszcze raz - ze zrozumieniem.

Added: 10 października 2023, 12:57. Add an answer

Mateusz write:

Obok zasad rządzących endokrynologią, jakie wyżej opisałem, źródeł jest cała masa. Na przykład na https://karger.com/nen/article/112/2/115/825344 opisuje się wpływ melatoniny na hormony płciowe, a na https://www.nature.com/articles/244230a0 przedstawia się wpływ melatoniny i serotoniny na wydzielanie somatotropiny. Natomiast na https://www.proquest.com/openview/4f1960cb2c0458ebe5870b9de2c0dcb5/1?pq-origsite=gscholar&cbl=46504 można znaleźć informacje o wpływie melatoniny na niedociśnienie nastolatków po jej przedawkowaniu. To, że układ hormonalny działa jako całość, a hormony wzajemnie wywołują wzrosty lub spadki stężeń innych hormonów, stanowi pewną biologiczną zasadę. Stąd też układ hormonalny należy zawsze traktować jako całość. Poszczególne gruczoły i hormony nie działają w oderwaniu od pozostałych.

Added: 10 października 2023, 14:55. Add an answer

ONSEN® Expert write:

Wontekście melatoniny warto powoływać się bezpośrednio na źródła naukowe. Mateusz podał już przykłady badań (Karger, Nature, ProQuest), które opisują jej wpływ na układ hormonalny, w tym hormony płciowe, somatotropinę i ciśnienie krwi u młodzieży. To potwierdza, że melatonina oddziałuje szerzej niż tylko na sen, a cały układ hormonalny należy traktować jako powiązaną całość. Jest to fakt, a fakty to przecież najbardziej uparta rzecz :)

Added: 23 września 2025, 09:43. Add an answer

Kasia write:

Biorę melatoninę od około 10 lat co noc w dawce 5 mg. Nie wiedziałam, że ma to jakieś skutki uboczne. Póki co nic złego się nie dzieje. Mam koleżankę Amerykankę, która od lat przyjmuje 10 mg co noc, podobno tam to normalna dawka. Ona również na nic się nie skarży.

Added: 28 października 2023, 00:14. Add an answer

ONSEN® Expert write:

Pozostaje się cieszyć. Wiadomo, że nie u każdego wywrze to zauważalny wpływ. Warto jednak mieć z tyłu głowy potencjalne skutki uboczne.

Added: 29 listopada 2023, 13:52. Add an answer

Bore write:

Po tygodniu brania jednej tabletki melatoniny przed snem u mnie występowało: splatanie w ciągu dnia, senność, osłabienie, zły nastój - już tego NIGDY nie zażyję. Nigdy. Po odstawieniu wrócił dobry nastrój i chęć życia.

Added: 1 lipca 2024, 09:42. Add an answer

Phoenix write:

Biorę melatonina ok 10 lat, 5mg na dobę. Wszystko się zgadza, od kiedy biorę melat. Mam migreny miesiączkowe. Innych skutków nie Zauważyłam.

Added: 26 stycznia 2024, 08:09. Add an answer

ONSEN® Expert write:

Jest więc to działanie niepożądane :)

Added: 6 lutego 2024, 12:49. Add an answer

Tomasz Wszółkowski write:

bez efektu-biorę 10mg. Mam 83lata.

Added: 20 listopada 2024, 12:56. Add an answer

ONSEN® Expert write:

Suplementowanie melatoniny jest być kwestią kontrowersyjną i zależy od wielu czynników, w tym od wieku i indywidualnych potrzeb zdrowotnych. Melatonina to hormon snu i nie należy z nią przesadzać. Zdecydowanie nie jest rozwiązaniem dla wszystkich. Każdy też może inaczej na melatoninę reagować. Nadużywanie środków hormonalnych bez konsultacji z lekarzem nie jest zalecane. W przypadku seniorów, u których naturalna produkcja melatoniny może być zmniejszona, suplementacja może pomóc w regulacji rytmu dobowego i poprawie jakości snu. Jednak nawet w takich przypadkach ważne jest, aby nie tylko wybierać odpowiednią formę, ale również zwracać uwagę na renomę producenta i skład produktu. Nie każdy preparat melatoniny jest stworzony tak samo, a skuteczność może wahać się w zależności od wielu czynników, w tym od stężenia, formy i dodatkowych składników. Przed rozpoczęciem jakiejkolwiek suplementacji zawsze warto skonsultować się z lekarzem, aby upewnić się, że produkt jest bezpieczny i odpowiedni dla danej osoby, a także aby dostosować dawkowanie do indywidualnych potrzeb.

Added: 15 stycznia 2025, 09:46. Add an answer

jerzy write:

Melatonina to wielkie oszustwo. Po zażyciu jest bezsenność i ból głowy.

Added: 30 listopada 2024, 13:01. Add an answer

ONSEN® Expert write:

Generalnie jej nie polecamy ;)

Added: 15 stycznia 2025, 09:35. Add an answer

Marcin write:

Niewygodnie się czyta tekst z tak ogromną liczbą pogrubień.

Added: 16 stycznia 2025, 12:26. Add an answer

ONSEN® Expert write:

Weźmiemy to pod uwagę :)

Added: 26 czerwca 2025, 09:11. Add an answer

Wiesław write:

dr. Bartek Kulczyński na You Tube zawarł informację na temat melatoniny a raczej o jej ważnej roli w organiżmie. To co wy piszecie w żaden sposób nie pokrywa się z jego przekazem. Dawka bezpieczna to 10 mg melatoniny na dobe. Omówił ponad 10 przypadków pozytywnych w jej zażywaniu i żadnych skutków ubocznych powołując się na najnowsze badania naukowe i tym się oparł. Proszę ustosunkować się do jego informacji i przekazu czy ma rację.

Added: 1 września 2025, 21:17. Add an answer

ONSEN® Expert write:

Dziękujemy za komentarz! Temat melatoniny budzi wiele emocji i jest przedmiotem badań naukowych. W naszych artykułach opieramy się na publikacjach medycznych i stanowiskach instytucji zdrowotnych. Nie jesteśmy od tego, aby krytykować czy popierać konkretne osoby, szczególnie nie znając ich intencji. Obserwujemy kolejne wyniki badań, aby zawsze podawać jak najbardziej aktualne informacje.

Added: 23 września 2025, 09:27. Add an answer

Walter write:

Jak wpływa substytucja melatoniny na poziom testosteronu? Niektóre źródła podają ze obniża poziom testosteronu u zwierząt ale jak jest u człowieka a przede wszystkim u mężczyzn

Added: 6 listopada 2025, 20:30. Add an answer

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The dark side of melatonin for sleep - is it really safe?

How does melatonin affect sleep?

What are the side effects of melatonin?

Can melatonin be overdosed?

How does melatonin impact the hormonal system?

Who can take melatonin for sleep and when?

What else helps with sleep besides melatonin?

FAQ: Melatonin for sleep

Is it worth taking melatonin for sleep?

How many hours do you sleep after taking melatonin?

What are the side effects of melatonin used for sleep?

Can melatonin be overdosed?

Can melatonin be taken daily?

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