Melatonin Side Effects and Can You Overdose?

If you can’t sleep, you’re not alone, and you may be among those who turn to melatonin for sleep. In the U.S., more than 36 percent of all adults report sleeping on average for less than seven hours per night.

For those ages 25 to 54, it’s an even larger percentage. If you’re a working adult, it’s possibly even worse — 33 percent of working adults reported sleeping six hours or less per night in 2017–2018, up from 28 percent in 2008–2009.

The pandemic made sleep issues even worse. According to a survey from the American Academy of Sleep Medicine, a full third of Americans are sleeping worse than they did before the pandemic.

No problem. Just take a melatonin gummy!

Well, not so fast, as more people are taking melatonin supplements than ever before in order to get better sleep, and some may even be using it at dangerously high levels — what’s known as melatonin overdose — according to a new Journal of the American Medical Association study.

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Let’s be honest: Many people buy it because it’s marketed very well. It comes in yummy, colorful gummies and seems like a terrific natural supplement to aid sleep.

But we still don’t know the implications for taking melatonin for the longer term, whether in adults or kids, and studies have revealed scarce evidence showing that it works for sleep difficulties. Let’s take a deeper look …

What is melatonin?

Melatonin is a hormone that makes you feel tired and facilitates you falling asleep, so it’s critical that your body makes enough of it at the right time. Your body creates it in your brain’s pineal gland, and it helps regulate your sleep-wake cycle.

The levels of melatonin start to increase at dusk, and they reach their peak levels by the middle of the night and start decreasing as dawn approaches. Melatonin naturally blocks signals in your brain that encourage wakefulness, thus helping you feel drowsy as you approach bedtime.

There’s evidence that high-energy light exposure at night (once it turns dark outside) — increasingly common in many households — suppresses release of the hormone melatonin. Lower melatonin levels can make it harder to fall and stay asleep, and now emerging studies have suggested it may also be linked with other health problems.

Melatonin supplements are marketed as natural sleep aids, and many melatonin supplements contain genuine natural ingredients. However, remember that a melatonin supplement is a lab-made version of your own hormone by the same name.

The supplement melatonin is supposed to help regulate the body’s sleep cycle and aid with several sleep problems, such as jet lag, insomnia, shift work sleep disorder and delayed sleep-wake phase (circadian rhythm sleep) disorder. There’s even some evidence that melatonin can help relieve cluster headaches.

Melatonin overdose

According to the JAMA study, consumption of melatonin supplements was only at 0.4 percent of the U.S. population in 1999–2000 but grew to 2.1 percent  in 2017–2018 — that’s a fourfold increase in nearly two decades. During the pandemic, consumption further increased.

Looking at Nielsen data, American consumers spent $825 million on melatonin supplements in 2020 — that represented a whopping 43 percent year-over-year increase.

Typically a standard melatonin dosage is five milligrams per day, for a short time period. The study revealed that a growing subset of adults are taking dosages that go well beyond the five-milligram standard.

Additionally, it turns out that actual content of melatonin in some marketed supplements can be up to 478 percent higher than the labeled content. In fact, a 2017 study in the Journal of Clinical Sleep Medicine showed that the amount of actual melatonin in more than 71 percent of supplements was inaccurate by a 10 percent margin.

This further indicates that the majority of sellers mislabel how much of the hormone is in their melatonin gummies or pills.

As the study reminded us, unlike drugs and food, melatonin is not fully regulated by the U.S. Food and Drug Administration. As a result, there are no federal requirements that companies test their melatonin supplements to be sure they contain the amount of the hormone advertised.

In a study of 30 commercial melatonin supplements, it found that more than a quarter contained serotonin. According to the National Center for Complementary and Integrative Health (NCCIH), this is a hormone that can have harmful effects even at relatively low levels.

Plus, accidental ingestion of serotonin can cause serious issues with any individual who is also taking antidepressants, migraine medications, etc.

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Lastly, while the general recommendation is to take only when needed (with many melatonin product labels simply saying “take as needed”), many people who take melatonin resort to taking it nightly.

Is that safe? According to the NCCIH, there is not enough information on the long-term effects to make a definitive determination, despite it seemingly posing few risks for most people in recommended doses.

Melatonin side effects

As a Nutrition Journal study pointed out, a natural sleep aid with limited side effects would be far preferable than a prescription sleep drug with more significant or even damaging side effects. Welcome melatonin, a sleep supplement considered generally safe for short-term use.

Compared to many sleep medications, you are unlikely to become dependent, have a diminished response after repeated use or experience a so-called hangover effect with melatonin.

That said, for some people, melatonin side effects can include:

• dizziness
• headaches
• nausea
• irritability

Less common side effects of melatonin include:

• vivid dreams or nightmares
• daytime sleepiness
• short-term feelings of depression
• stomach cramps
• decreased libido
• breast enlargement (gynecomastia) in men
• reduced sperm count in men

“Melatonin nightmares” are typically a sign that you need to decrease how much you’re taking. You never want to start out with the max dose. Instead, you want to start small and gradually increase if needed.

Remember, more isn’t better. Just one milligram can suffice, while many supplements contain five to 10 milligrams per serving.

Similarly, doctors recommend that you take melatonin like a pain reliever, for a short period of time, not habitually.

If you experience drowsiness the morning after taking melatonin, try taking less. Never drive or use machinery within five hours of taking it.

If you take an excessive amount unintentionally, seek medical attention immediately.

Drug interactions

Melatonin can also decrease the effectiveness of some medications, while actually decreasing side effects from others. Here are some possible drug interactions to be aware of:

• Antidepressant medications
• Antipsychotic medications
• Benzodiazepines
• Birth control pills
• Blood pressure medications
• Beta-blockers
• Blood-thinning medications (anticoagulants)
• Interleukin-2
• Non-steroidal anti-inflammatory drugs (NSAIDs)
• Steroids and immunosuppressant medications
• Tamoxifen

Speak with your doctor first before taking melatonin if you have any ongoing health concerns or are currently taking any other medications.

Does melatonin work for sleep?

Research has suggested that supplementing with melatonin may help people with disrupted circadian rhythms, such as people who work the night shift and people who have jet lag. Supplementation may also help individuals sleep better who have chronically low levels, like people with schizophrenia, who have poor sleep quality.

One randomized, double-blind trial found that two milligrams of melatonin prolonged release (PR) given one to two hours before bedtime was associated with significant improvements compared to a placebo in sleep quality and length, morning alertness, and health-related quality of life. The study also found that whether the melatonin dosage (two milligrams PR) was for the short or long term, there was no dependence, tolerance, rebound insomnia or withdrawal symptoms.

Studies also have uncovered evidence that melatonin is effective in advancing sleep-wake rhythms in people with delayed sleep phase disorder. Delayed sleep phases are experienced by those who struggle with waking up later in the morning than is considered normal/socially acceptable.

Taking melatonin can help people with this sleep problem fall asleep a bit sooner, although it can take some trial and error to determine the best timing and dose.

Other studies have demonstrated that for normal sleep issues, such as for the initiation of sleep and sleep efficacy, the data doesn’t confirm a positive benefit as of yet. One study indicated that no recommendation can be proposed for the use of melatonin in shift workers.

One issue that many people don’t take melatonin properly, as timing can be key. Rather than taking right before bed, it’s recommended by experts to take it several hours before bed in order for it to be effective.

There are some other potential melatonin benefits that warrant further research, such as:

• Supporting eye health: Research has revealed that it may be helpful in treating or preventing age-related eye disease, such as macular degeneration and glaucoma.
• Protecting cognitive health: Melatonin has been found to have antioxidant activity that appears to help delay or prevent the development Alzheimer’s disease, and this hormone possesses neuroprotective effects that may aid in treating depression.
• Helping with acid reflux/gastroesophageal reflux disease (GERD): There is evidence that this supplement may help treat and/or prevent acid reflux and GERD, among other digestive and esophageal issues.
• Migraine relief: Several studies have unearthed evidence that taking melatonin can help relieve migraines and even lower the frequency with which migraine sufferers deal with attacks.
• Tinnitus treatment: It appears taking this hormone as a supplement can help decrease the intensity of tinnitus symptoms and even promote better sleep in chronic tinnitus sufferers, according to research.

Final thoughts

• Should you take melatonin? While still considered safe in recommended doses, do not take for an extended period of time, and do not exceed five milligrams. In fact, start at a lower dosage. Also, make sure you buy from a reputable company.
• Don’t take right before bed. Instead, supplement with it several hours before you know your head will hit the pillow.
• For people with sleep issues, they need to determine whether or not it helps. For many, it may not, while those with more serious sleep issues, like shift work sleep disorder or circadian rhythm sleep disorder, may see an immediate benefit. It can also be used for jet lag.
• If you are young or old and have sleep issues, it’s still better to improve your sleep habits before opting for this hormone supplement. For example:
  • turn off your screens (blue light) at least an hour before bed
  • keep to a consistent sleep-wake cycle
  • sleep in a cool and dark room
  • avoid late evening exercise
  • avoid caffeine after 2 p.m.
  • use your bed for only sleep (and sex) rather than watching TV or reading
• As indicated in the JAMA study, the growing popularity of melatonin and its expanding therapeutic potential — such as evidence of its antioxidant and anti-inflammatory properties — warrant further study, including a careful examination of its long-term safety profile.