What is melatonin and does it help with jet lag and insomnia?

From brisbanetimes.com.au

Some jetsetters, shift workers and insomniacs use melatonin to help them nod off or stay asleep. What is it? How does it work? Is it safe and what don't we know about it yet?

Melatonin has various nicknames: the "hormone of darkness", the "sleep hormone" or the slightly spooky "Dracula of hormones". Melatonin is released when the sun goes down, telling us when it’s time to sleep. The term itself comes from the Greek word "melas", for dark, and "tonin" from seratonin, a related hormone.

Melatonin supplements are popular with shift workers, insomniacs and long-haul travellers trying to avoid jet lag and, increasingly, bleary-eyed parents are asking doctors to prescribe it for their sleep-deprived – and sleep-depriving – offspring.

What is melatonin, and what is it for?

Melatonin is a hormone made in the pineal gland, located deep inside the human brain, that works closely with our internal circadian clock.

When darkness falls, the pineal gland releases a surge of melatonin. This prompts our core temperature to drop a little and readies our body for sleep. Those melatonin levels remain high throughout the night, until a sudden drop in the morning tells our bodies it's time to wake up and face the day.
In short, melatonin is what makes us sleepy.

Derived from an amino acid called tryptophan – which is also present in milk and is likely the reason we are told warm milk before bed will help us sleep – melatonin also occurs naturally in some foods including cherries, rice and peanuts.

It can be bought in pill, liquid and chewable forms and is a popular dietary supplement in some parts of the world.
It was first discovered in 1958 by an American dermatologist who found it could lighten a frog's skin. A synthetic version was approved in Australia in 1987 for use in female sheep but it took another decade for Australia's Therapeutic Goods Administration (TGA) to approve it for human use and, even then, only by prescription.

Experts say taking melatonin an hour or two before bed can help to shift the body's internal body clock forward. This is especially useful for those suffering from jet lag and can help shift workers to reset their clocks so they fall asleep at more social hours.

I work night shifts. Will melatonin help me?

It might. About one in six Australian workers (16 per cent) are shift workers, according to the Sleep Health Foundation. And it's commonly accepted that shift workers are getting less sleep than the rest of us.
A recent federal government report into the sleep health of Australians also found that shift work and, in particular, night shifts can disrupt sleep patterns and lead to serious health problems. "Shift work has been linked to the increased risk of obesity, sleep disorders, mental health conditions and cancer," the report found.

Enter better sleep routines, smarter exposure to light and melatonin supplements.

"It's the exposure to light for shift workers late at night that was considered a possible carcinogen by the World Health Organisation," says Associate Professor Sean W. Cain, a circadian biologist at Monash University. "It's likely that if you are suppressing your melatonin a lot over many years, you are slightly increasing your chance of developing or growing tumours."

Experts suggest that a shift worker who is finishing late and taking hours to fall asleep may benefit from taking a melatonin pill as soon as it is safe to do so after finishing work (it makes you drowsy). Coupled with a sensible wind-down routine, it may help to bring the body clock forward and ensure beauty sleep comes a little quicker.

But it is not enough in itself. "If you have a naturally delayed body-clock you do need to take some care and attention with your routines, otherwise you will lapse back," says Associate Professor Darren Mansfield, deputy director of Monash Lung and Sleep and head of the Monash Health sleep service. "If your [body's] natural preference is to be delayed, dim the lights, take some melatonin [and get] lots of outside light the next day."

I can't sleep. Will melatonin help with insomnia?

Insomnia is a common problem, with a 2013 study published in the Medical Journal of Australia finding up to one-third of Australians struggled to fall asleep or to stay asleep. Melatonin is just one option to help combat sleeplessness – but a popular one.

There are two forms of melatonin supplements: a rapid release form that is taken an hour or two before you want to nod off; and a slow release form that, essentially, tops up your melatonin levels all night and which is useful for helping you stay asleep.

The slow-release form is the standard prescription available at pharmacies. "Think of that as drip-feeding into the system over the course of the night, which will supplement the existing melatonin levels overnight in a relatively modest way," says Associate Professor Mansfield. "It will increase the levels but not to a massive degree."

But, like many other medical conditions, there is no easy fix for insomnia. "The only good in all that is a lot of people grow out of it," Associate Professor Mansfield says.

Is melatonin safe for children?

Yes – with some caveats.
Paediatrician Dr Anthea Rhodes, director of the Royal Children's Hospital national child health poll, has been prescribing melatonin to children for more than a decade. She says melatonin is not addictive – so children are unlikely to become dependent on it – and side effects are rare. "Having prescribed melatonin for many years to many children, I have not experienced significant issues with side effects," she says.

Unlike sleeping pills or aids like phenergan, melatonin is not a sedative. "I often say to parents, 'If you have a child who is really wired or wide awake, a dose of melatonin is not going to knock them out'," she says.

Typically used to help children with problems falling asleep, or staying asleep, melatonin is also a popular treatment for children with ADHD, autism and other developmental disabilities.  

Paediatric doctors say the medication is safe enough to be dispensed over the counter but a 2017 application to allow over-the-counter sales was rejected, in part due to fears it could be misused when treating children with behavioural or disciplinary issues.

But Dr Rhodes says that isn't a bad thing, as it gives doctors a chance to work with families to rule out other sleep-related problems first. This could include a child suffering from anxiety; how, when or where they are being settled to sleep; and the use of blue-lit screens or devices before bed.

Dr Rhodes says a good bedtime routine is the key to a good sleep. It's only when that fails that melatonin should be considered. "Used with a good bedtime routine, melatonin can be a game-changer for families," she says.

What are its side effects?

The most common side effect of melatonin is drowsiness. But that's also the point of it! Some users get headaches, nausea or even abnormal dreams but experts working with it on a regular basis agree that there are few documented side effects. "Having prescribed melatonin for many years to many children, I have not experienced significant issues with side effects," says Dr Rhodes.

Associate Professor Mansfield agrees. "It is a relatively harmless medication," he says. "It has been pretty much out in the open market now for decades, and dispensed in huge quantities. And we are not out there in the real world seeing real problems. We would probably regard it as a safe medication with no known serious side effects. There are people who pipe up and say, 'but we don't have safety data'. Well that is sort of true but it seems pretty safe."

Once flagged as a potential contraceptive because it was found that extremely high doses (more than 50mg) could cause infertility, early studies found it simply wasn't effective enough in preventing conception. "It can interfere in other hormonal systems, at very high doses, [and] it can affect [menstrual] cycles," Associate Professor Mansfield says. There is some evidence that the side effects of melatonin could be heightened in women taking the contraceptive pill or anyone on diabetes medication but more research is needed.

Speculation also remains rife that it can affect your mood. Associate Professor Cain spends a lot of his time researching, writing and talking about light and darkness. He says one of the actions of melatonin is to block responsiveness to light.

"Light can elevate your mood, that's why people use light-therapy devices for depression," he says. "So if your system is less sensitive to lights, it might be giving your brain fewer alerting and mood-elevating signals. So if melatonin reduces your responsiveness to light, I could imagine that it could increase mood vulnerability to depression. But that's all speculation."

What is not speculative are the number of studies that have found melatonin is safe when used for up to six months. There is also some evidence that it can be used safely for up to two years. However, experts generally agree that long-term use of melatonin needs more investigation.

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