What is melatonin? Does it help with sleep?
Melatonin is commonly promoted as a sleep aid. In many countries it is available over the counter, so quite widely used. In Australia it requires a prescription, with some formulations in homeopathic doses able to be found in health food stores. But is melatonin helpful for sleep?
What is melatonin?
Melatonin is a substance that is normally produced in the brain by the pineal gland. When we receive light to specific receptors in the back of the eye a signal comes from the eye to the pineal gland in the brain and suppresses the production of melatonin. When light decreases melatonin production gradually increases and remains high during when it is dark. When we are again exposed to light in the morning melatonin production is suppressed and melatonin levels drop.
In years gone by melatonin for use as a treatment was produced from animals’ brains such as cows. But for many years this has not been the case and melatonin that is used as a treatment is all synthetically produced and therefore there is no risk of contamination or infection.
What does melatonin do to sleep?
Melatonin has two main effects on sleep:
1. Hypnotic Effect: Melatonin has an effect that can make people feel more sleepy, get to sleep more quickly and stay asleep for longer. Not everyone is susceptible to this effect and studies of using melatonin as a sleeping pill have generally been in people that are older. This is why in Australia it is marketed for use in people over the age of 55 for up to three months only, as this is where there is the best evidence to support its use as a sleeping tablet.
A meta-analysis summarising the research for melatonin as a sleeping tablet was published in PLOS One in 2013. It showed that melatonin got people to sleep 7 minutes quicker, and kept them asleep 8 minutes longer as well as improving sleep quality. The authors concluded that melatonin was effective, but less effective than other prescription medications such as benzodiazepines. However, because of the low rate of side-effects with melatonin it was worth considering.
In other countries where melatonin is more widely available it is often used as a sleeping tablet but people report that it is variably effective. Some people report they get a good response to melatonin whereas others find it does not do much in terms of helping their sleep. This most likely relates to differences in genetic makeup and susceptibility to the sedating effects of melatonin.
2. Clock-shifting Effect: This is where there is the best evidence for use of melatonin, to shift the internal body clock in conditions where it is out of synch such as jet lag. There is also increasing research on use of melatonin for the circadian rhythm disorder, delayed sleep-wake phase disorder, where people have trouble getting to sleep and find they are waking progressively later each day.
How is melatonin taken?
Decisions about use of melatonin should be made in consultation with your healthcare professional, as in Australia it is a prescription medication.
In general if it is being used as a sleeping tablet for its sleep-promoting effects it should be taken around one hour before people intend to go to sleep. However, if the use is more for its clock-shifting effects it is preferable to take it some hours before people wish to go to sleep.
Bear in mind that by taking melatonin you are trying to give the brain a signal that it is dark outside so we generally aim to take melatonin around the same time that the sun is going down to help the body better synchronise with the normal light-dark schedule of the environment. It’s also why being careful about exposure to light after taking melatonin is important, as light, particularly of the blue-green wavelength, can suppress melatonin production. For more information on managing light see the blog post on light therapy and video on managing circadian rhythm disorders.
What forms of melatonin are available?
In Australia the only formulation of melatonin that is readily available is called Circadin. It is a slow-release 2 mg preparation that is available only on prescription. The best evidence for the use of Circadin is trials in people over the age of 55 for use for up to three months in the treatment of insomnia, so this is how it is approved for use in Australia. This also means that the information in the packets of Circadin sold in Australia focus on it’s use in this way.
Other formulations of melatonin can be made up to order by a compounding pharmacy. It can be made in doses ranging from 0.1 mg up to as high as 18 mg and in suspension or capsules. It can also be made in either short-acting, rapid-onset or longer-acting slow-onset formulations. In general when using melatonin for its clock-shifting effect studies have used shorter-acting formulations taken some hours before desired sleep onset. But the data is very variable and there are no hard and fast rules or strong data to direct which formulation should be used in all circumstances. In addition there is a lot of variability in the response to melatonin so while some people will respond well to quite small doses such as 0.1 mg to 0.5 mg, other people find they need higher doses to get an effect.
Blindness and melatonin
Melatonin has also been used for treatment of sleep problems in people who are totally blind. People with a type of blindness that detection of a light signal in the back of the eye, and therefore don’t have light regulating melatonin production, develop an irregular sleep-wake pattern usually consistent with non-24 sleep-wake rhythm disorder. Taking melatonin at a regular time can help to regularise their sleep pattern. In clinical trials of people who are blind, higher doses of melatonin have been used such as between 6-18 mg. There is also research using the melatonin receptor agonist, tasimelteon (sold as Hetlioz), in people who are blind and have non-24 sleep-wake rhythm disorder. Hetlioz is not available in Australia but has been approved for use in the US, and recently Europe.
What are common side effects from melatonin?
Melatonin is usually quite well tolerated and in general is considered safe. The most common side effects are feeling more sleepy the following morning, headaches and dizziness. The main areas where I will be more cautious about using melatonin are:
- Puberty and pregnancy – Melatonin can have an effect on hormones, particularly those involved in pubertal and foetal development. So, whilst I’ll often use melatonin in teenagers who have trouble getting out of bed, I’ll try to use it for as short a period of time as possible, and will avoid using it during pregnancy.
- Immune disorders – Melatonin can increase the activity of the immune system, so in people with auto-immune disorders, or who are on immune suppressing treatment, I’ll try to avoid using melatonin.
- Restless legs syndrome – There have been some small studies showing that melatonin increases restless legs symptoms (RLS). For that reason, if people have severe RLS, with difficult control symptoms, I’ll try to avoid melatonin
- Seizure disorders or epilepsy – This is controversial, as although there is animal research that shows melatonin can reduce the threshold for seizures and make seizures more likely, there are also studies showing it’s use in people with seizures showing a reduction in seizures. People with seizures should discuss use of melatonin with their epilepsy specialist before starting melatonin.
Related posts & links:
- Cognitive behavioural therapy for insomnia
- What is the circadian rhythm? – video
- Managing the circadian rhythm – video
- Medication for insomnia
- Melatonin – can it reduce delirium in people in hospital? – The Age
- Melatonin.com – online provider of melatonin
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