Taking melatonin used to be the habit of the jet-lagged traveller as a way to shortcut the weary bewilderment of a confused body clock. Then it was discovered by parents. “Pretty much all the kids I see, by the time they get to me, they’ve used melatonin,” says Dr Chris Seton, a paediatric sleep physician at the Woolcock Institute and the children’s hospital at Westmead in Sydney.

Melatonin is a hormone produced by the brain’s pineal gland in response to darkness; its nickname is the hormone of darkness. Levels increase at night, which helps precipitate sleepiness through its interactions with the central clock and circadian rhythm, then decrease towards dawn, precipitating wakefulness.

But in some people, including children, this cycle is disrupted in some fashion. And for the parents of those children, the sleep deprivation that plagues both their child and them is a unique misery.

Most endure it with the reasonable hope that things will improve over time. But what happens when they don’t? Particularly for children with neurodevelopmental disorders such as autism and attention deficit hyperactivity disorder – but even for neurotypical children – sleep problems can persist well into teenage years and even beyond. It can be a desperate situation for parents, compounded by the often months-long waiting lists to see paediatric sleep specialists.

The use of melatonin as a sleep aid has skyrocketed in recent years. In Australia, melatonin products for adults were made available over the counter from pharmacists in 2020. There are also prescription-only products that are indicated for use in children with autism spectrum disorder or a neurodevelopmental disorder called Smith-Magenis syndrome associated with sleep disturbances.

And there is a flourishing online market in melatonin-containing products aimed at children. They’re fruit-flavoured, available as chewable tablets, gummies and drops, and marketed with all the imagery you would expect: a sleeping child nestled in a crescent moon, a cute monster tucked in bed with its teddy bear, a child curled up on a pillow. There’s no data available on how sales of these have changed over time, but paediatricians and child sleep specialists have seen a significant increase in the number of their patients using them in the past five to 10 years.

And over that time, there has also been a greater awareness of the importance of healthy sleep for children and adults.

“Sleep has risen to the agenda of the health narrative in the community,” says Prof Sarah Blunden, the head of paediatric sleep research at Central Queensland University. “Sleep is a big thing – a little bit like stress was in the 80s.”

“The vast majority of people that I see in my clinic are told by their mate at school or their parenting group, ‘why don’t you try melatonin because it’s natural’,” says Blunden. “It’s not natural. It’s in a bottle. It’s synthetic.”

There are some concerns about such widespread use of over-the-counter or online melatonin supplements in children. Firstly, most of the clinical trials of melatonin to help sleep in children are done in children with neurodevelopmental disorders such as autism and Smith-Magenis, where sleep difficulties can affect up to 80% of children.

The good news is there is substantial evidence that melatonin – combined with behavioural sleep interventions – can help many children with these disorders to get to sleep and stay asleep. One study comparing a slow-release form of melatonin with inactive placebo in 125 children and adolescents with autism spectrum disorders and other neurogenetic conditions found the treatment was associated with a faster time to sleep and longer sleep time.

Beth Malow, a professor of neurology and paediatrics at Vanderbilt University Medical Center in Tennessee, is one of the leading researchers of the effectiveness of melatonin in children with neurodevelopmental disorders. “There are kids, in my clinical experience, who it works really, really well for and that’s most kids,” Malow says. “In some kids even immediate-release melatonin helps them stay asleep – it’s almost like it turns on a sleep switch.”

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There are fewer studies of melatonin in neurotypical children and adolescents, but Malow says it can also help those with a disorder known as delayed sleep phase, where the circadian rhythm is disrupted so people go to sleep late and wake up late. “It may very well be because they’re making less melatonin, or their melatonin is delayed,” she says. There’s also evidence that melatonin could help children and adolescents with ADHD.

Malow’s own research, which was partly supported by a manufacturer of slow-release melatonin, also found no evidence that up to two years of prescribed melatonin use had any negative effects on weight, growth or puberty and development melatonin in this group of children.

However, she always stresses to parents that despite its safety, melatonin is still a drug and needs to be treated like one. “You really want to make sure that the paediatrician knows about it and what you’re getting, what dose you’re getting,” she says.

Melatonin supplements are also increasingly implicated in accidental poisonings abroad. A US study found the number of reports of children accidentally taking melatonin increased by 530% between 2012 and 2021. Among more than 260,000 reports to poison control centres during that time, there were about 4,000 hospitalisations, 287 children admitted to intensive care and two deaths, both in children aged under two years.

The second issue is that parents or doctors might leap to melatonin as a treatment for a child’s sleep problems without looking for other possible explanations. “You have to look at medical co-occurring conditions,” Malow says. “If a child has sleep apnoea, melatonin isn’t going to be that effective; they’re going to wake up from their apnoea or their sleep is going to be dysregulated from that.”

Sleep problems can also be the result of mental health issues such as anxiety and depression, physiological issues such as low iron and especially poor sleep behavioural practices such as screen use before bedtime, which can affect melatonin production in the brain. This leads to the third potential issue with jumping too quickly on the melatonin bandwagon: it shouldn’t be used without first trying behavioural interventions.

“What I am concerned about is that some families that might use it as a shortcut for sort of good sleep practices,” says A/Prof Margot Davey, a paediatric sleep specialist and director of the Melbourne Children’s Sleep Centre at Monash children’s hospital. “If you’re seeing children or teenagers with difficulties falling asleep or maintaining sleep, it’s important to look at behavioural and schedule changes, which we know are helpful,” she says.

These changes include limiting the use of screens before bedtime, improving the sleep environment, instituting bedtime routines and looking at what foods the child or adolescent is eating before bedtime.

While these take time and effort, Davey says they are very successful. “Obviously, there will be families where it’s more challenging or children aren’t responding, and then I have no problems with those families doing a second-line treatment and thinking about melatonin,” she says.

The widespread use of over-the-counter or online melatonin supplements in children presents another issue: parents can’t always be sure of what the supplements contain. A 2017 study from Canada that sampled 30 commercially available melatonin supplements found the actual melatonin content ranged from 83% less to nearly five times more than what was on the label. About one-quarter of the supplements also contained the neurotransmitter serotonin, which is used to treat neurological disorders.

Blunden is keen to combat the idea that melatonin is “natural” and therefore harmless and can be used without care or caution. She wants a focus on educating parents and doctors about when and how this drug can and should be used, but also more studies to expand access to melatonin for other children and adolescents who could benefit.

Melatonin is, she says, looking pretty good. But we need to know more about what exactly it is we are giving to our children. “We need to ramp up studies, we need to ramp up the information,” she says. “We can’t just sit on our hands and wait for this to happen.”