Let’s put melatonin misinformation to rest

By Leonie O’Sullivan, June 8 2023—

After a global pandemic and the pressures of university, more students may find themselves turning to melatonin, a hormone that regulates our sleep-wake cycle, to get some shut-eye. But is there any science to suggest melatonin is a viable nightcap?

One of the top videos on TikTok with the hashtag melatonin, shows an individual in bed with their comfy pyjamas on, book in hand, candles lighting and a cloudy melatonin vape. After a quick scroll through the top videos with this hashtag, it is clear that there’s a lot of melatonin misinformation circulating, not only to influence you to buy melatonin but also pointing out the so-called serious side effects of melatonin to persuade you to purchase a different sleep aid. Let’s get right into the nitty-gritty and answer some questions about melatonin supplements.

Does taking an exogenous or an external source of melatonin decrease your endogenous or natural levels of melatonin?

One study analyzed urine samples from participants who had taken exogenous melatonin for six months, two weeks after withdrawal. In your body, melatonin is broken down into a key metabolite called  6-sulphatoxymelatonin (6SMT). The presence of 6SMT in urine is a reliable marker for endogenous melatonin production. Suppression of endogenous melatonin was not observed in this study, and it was confirmed that the metabolite was from endogenous melatonin and not from residual exogenous melatonin. It is important to note that this study was carried out by Neurim Pharmaceuticals Ltd, which manufactures prolonged-release melatonin (PRM) (Circadin®), but this result is supported by previous reports from Mallo and Matsumoto. 

Is melatonin completely banned in the U.K.? 

Technically, no. In the U.K. melatonin is a prescription-only medication, meaning there is no over-the-counter (OTC) access. Melatonin is considered medical by function and is classed as a medicine and not as a health supplement, in many countries. 

Is it safe to take melatonin supplements?

Short-term studies in adults have proven melatonin to be safe but there is limited data on long-term use. There have only been three double-blind, placebo-controlled studies which have not revealed any serious adverse effects of melatonin in the long term. 

Extreme care must be taken to ensure melatonin is out of reach of children. In 2020, melatonin was the highest reported ingested substance among children to national poison control centres in the dietary supplements/herbals/homeopathic category. Sadly, two children aged three months and one year have passed away due to melatonin poisoning. 

Since melatonin is classified as a natural health product in the U.S. and Canada, it is regulated less strictly by the FDA and Health Canada. This has had some consequences. A study from the University of Guelph in Ontario evaluated the amount of melatonin in 30 commercial supplements. The researchers found that the products deviated from −83% to +478% of the labelled content. This means that if a label says each unit contains 1 mg of melatonin — it could actually contain anywhere from 0.17 mg to 4.78 mg. The products with the most basic ingredients, generally tablets with melatonin and filler such as cellulose derivatives or silica, were the most reliable. Chewable tablets and capsules were found to be the most variable. Serotonin, an important neurotransmitter and a controlled substance in Canada, was found in eight of the supplements. 

What are the side effects of melatonin?

Side effects are uncommon and vary from daytime grogginess, headaches and dizziness to hypothermia. More serious adverse effects include agitation, fatigue, mood swings, nightmares, skin irritation and palpitations. Most of these effects resolved over a few days or immediately once melatonin supplementation was halted. There is limited data regarding long-term side effects.

Does melatonin inhibit oral contraceptives (OCs)? 

Experts say there is almost no chance that melatonin could reduce the efficacy of OCs — but on the flip side, this combination could actually increase the effectiveness of melatonin. One small study reported that when melatonin is taken with OCs, melatonin concentration in the blood is four times higher than in individuals taking melatonin without OCs. 

Can melatonin help with COVID-19 prognosis?

Melatonin, which many individuals have started to take due to the stresses of living through a pandemic, may be helping us in more than one way with COVID-19. A clinical trial compared the standard therapeutic care for COVID-19 with and without melatonin as an adjuvant. The mortality rate of the control group (patients not receiving melatonin) was 17.1 percent whereas the mortality rate of those given the melatonin adjuvant was much lower at 1.2 percent. 

If you are thinking about taking melatonin, or if you are already taking this sleep aid — it is a good idea to have a conversation with your doctor. If your difficulty sleeping is due to an underlying condition such as anxiety, sleep apnea, restless legs syndrome or depression, melatonin may not be the right choice for you. Melatonin is suggested to be used for temporary insomnia, jet lag, shift workers and the night owls of the world who may want to turn back their internal body clocks. As we get older, we may also benefit from melatonin supplementation, as our bodies slow down the production of this hormone. 

Take caution when considering the form of melatonin you choose to consume. The concentration of melatonin in chewable tablets is often unreliable. Melatonin vapes or personal diffusers have become a popular choice, but dosing is often inaccurate with vaping, and your vape may contain some potentially harmful chemicals. If you do decide to start taking melatonin, stick to products with the most basic and simple ingredient lists and start on a low dose. 

You can help your body wind down for some sleep by reducing the brightness of your room before sleeping. Natural melatonin production is triggered by darkness, so reducing your screen time or screen brightness before bed will also help your endogenous melatonin levels. Adjusting your diet to contain more melatonin-rich foods such as eggs, fish, pistachios, mushrooms and other foods may also help prevent you from counting sheep at night.  

The next time you are scrolling TikTok or other social media platforms, consider whether influencers are backing up their claims, or are trying to mislead you.