Melatonin prolonged-release tablets (Circadin) for insomnia

Published in Medicine Update

Date published: About this date

Health and medicines information in this article may have changed since the date published. This information does not replace advice from a health professional.

This Medicine Update is for people who are taking, or thinking about taking, prolonged-release melatonin.


Melatonin prolonged-release tablets (Circadin) can be used by people over 55 years of age to treat sleeping problems (insomnia) not caused by other physical or psychological conditions.

Medicines should only be used short term for sleep problems. Learning good sleep habits can be just as effective and lasts longer.

If you and your doctor think that a medicine is necessary, prolonged-release melatonin is an alternative to other sleep medicines that can have unpleasant side effects. Between 30% and 50% of people will probably get some benefit from prolonged-release melatonin — either in the quality of sleep, or the time it takes to fall asleep. It does not seem to affect the overall length of time spent sleeping.

Prolonged-release melatonin tablets do not seem to affect daytime alertness or cause addiction or withdrawal symptoms.

Prolonged-release melatonin is approved for use for up to 3 months.


What prolonged-release melatonin is

The active ingredient of this medicine is melatonin (pronounced mel-ah-TOE-nin).

Melatonin is a chemical produced naturally by the body.

Circadin is the brand name for a synthetic melatonin in the form of prolonged-release tablets.

This Medicine Update is not about other forms of melatonin.

What prolonged-release melatonin is for

Prolonged-release melatonin is used to treat primary insomnia.

Insomnia is a persistent sleep problem where people find it difficult to get to sleep or stay asleep, or they have poor quality sleep. This affects their ability to function properly the next day.

Primary insomnia is when this sleep problem is not caused by a medical condition, another medicine, use of illicit drugs, or external reasons such as a poor sleeping environment.

Sleep problems can be caused by:

  • a medical condition (for example, pain or depression)
  • another medicine
  • use of illicit drugs
  • a poor sleeping environment.

In which case, the sleep problem is known as ‘secondary insomnia’.

Who can take prolonged-release melatonin

You will need a prescription from your doctor for prolonged-release melatonin. (See What does prolonged-release melatonin cost?)

Prolonged-release melatonin is approved for treating primary insomnia in people who are over 55 years of age. Studies into the effectiveness of prolonged-release melatonin demonstrated the best results in people 55 years of age or older. It was not found to be particularly effective for people younger than this.

Speak to your doctor before taking prolonged-release melatonin if you:

  • are pregnant or are breast-feeding
  • are under 18
  • have liver or kidney problems
  • have an autoimmune disease.

An autoimmune disease is where the body is attacked by the immune system. Some examples include rheumatoid arthritis, multiple sclerosis, lupus and inflammatory bowel disease.

Prolonged-release melatonin is not approved for treating jet lag.

Prolonged-release melatonin is not suitable if you have secondary insomnia (see above).

No matter which type of insomnia you have, ask your health professional for advice about improving your sleep habits. This can be an effective way to solve sleep problems without taking medicines. See NPS resources with advice on how to get a good night’s sleep.

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How to take prolonged-release melatonin

Take one prolonged-release melatonin tablet at around the same time each night — 1 to 2 hours before going to bed. Do not take it much earlier as this may cause problems with waking early.

Swallow the tablet whole with water. Don’t crush, chew or break the tablet.

It’s best to take the tablet soon after eating, as this will help with the prolonged-release effect for this form of melatonin.

You should avoid drinking alcohol before or after taking a tablet. Alcohol interferes with the absorption of melatonin so that it may be less effective.

Ask your doctor how long to take prolonged-release melatonin for. It is approved for up to a maximum of 3 months (13 weeks). There is no evidence that the benefits are maintained when you stop taking it.

What does prolonged-release melatonin do?

The melatonin your body produces naturally usually increases as it is getting dark and continues to rise during the night. This helps to regulate the body’s sleep–wake cycle. It is thought that as we age, natural melatonin levels reduce and this may contribute to sleep problems.

Prolonged-release melatonin tablets provide your body with additional melatonin. This may improve your quality of sleep and morning alertness.

In clinical trials, prolonged-release melatonin helped improve some aspect of sleep (e.g. sleep quality, morning alertness) for between 30% and 50% of people. However, the same improvements were found in 20% to 30% of people taking a dummy pill (placebo).

The time it took to fall asleep was reduced by an average of 9 minutes. But there was no significant change in the length of time spent sleeping.

Important side effects of prolonged-release melatonin to consider

For a more complete list of possible side effects for Circadin (melatonin), see the consumer medicine information (CMI) leaflet available on our Medicines Finder page.

Ask your health professional about the possible side effects of this medicine before you take it. Always tell them about any changes to your condition if you're taking a new medicine.

To report possible side effects call the Adverse Medicine Events (AME) line on 1300 134 237 from anywhere in Australia (Monday–Friday, 9am–5pm AEST).

People with questions about their medicines or seeking general information about side effects can call the NPS Medicines Line on 1300 633 424 (Monday–Friday, 9am–5pm AEST).

People reported several different side effects in clinical trials. The most frequently reported common side effects were:

  • headache
  • respiratory infections
  • back pain
  • joint pain
  • feeling weak or tired.

Information on the side effects from taking melatonin for longer than 6 months is still limited.

Melatonin does not seem to be addictive or cause withdrawal effects after stopping.

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What else you should know about prolonged-release melatonin

Do not take melatonin with other medicines for sleep problems, including non-prescription or herbal remedies, as it may interact with them.

In particular, you should not take melatonin if you are taking the following medicines:

  • prescription sleep medicines such as hypnotics and tranquilisers (e.g. benzodiazepines, zolpidem — see list in Other medicines available for insomnia)
  • fluvoxamine, imipramine and thioridazine (used to treat depression or psychiatric problems).

It may also interact with:

  • carbamazepine (used to prevent seizures and convulsions)
  • cimetidine (used to treat stomach ulcers and heartburn)
  • oestrogen (contraceptives or hormone replacement therapy).

Check with your doctor or pharmacist before using these medicines together.

Use a medicines list to help keep track of the medicines you are taking. Take it with you each time you visit a health professional, or if you go into hospital.

Get an NPS Medicines List or download the free iPhone app.

Prolonged-release melatonin rarely causes daytime drowsiness, but it is not recommended that you drive or operate machinery for 8 hours after you take it. If you do feel drowsy during the day, you should consult your doctor.

Other medicines available for insomnia

There are ways to improve your sleep without using medicines — see Other ways to relieve insomnia for more information. Your doctor can also help you find out about cognitive and behavioural therapies for the treatment of insomnia. These have been found to be just as effective as medicines and have a longer-lasting effect on sleep.

Most prescription sleep medicines are only suitable for short-term use due to the risk of side effects and addiction.

Examples of prescription sleep medicines

Active ingredientBrand names
NitrazepamAlodorm, Mogadon
TemazepamNormison, Temtabs, Temaze
ZolpidemDormizol, Somidem, Stildem, Stilnox, Zolpibell
ZopicloneImovane, Imrest

Several complementary medicines — including chamomile, hops, lavender, passiflora and valerian — are used to treat insomnia. There is some evidence to suggest that valerian may be helpful (How to decide between melatonin and other medicines), but less for the others.

Avoid sedating antihistamines

People sometimes use medicines called sedating antihistamines to help them sleep. These are available over the counter at pharmacies.

But they are not suitable for treating insomnia, particularly in older people, because they quickly stop being effective. They can also cause unpleasant side effects such as dry mouth, constipation and blurred vision.

Examples of sedating antihistamines

Active ingredientSome brand names
DiphenhydramineSnuzaid, Unisom Sleepgels
DoxylamineDozile, Restavit

How to decide between melatonin and other medicines

Talk to your doctor or pharmacist about your insomnia. Remember, effective non-drug options are available and are probably more helpful than medicines in the long term.

Remember that benefits and side effects differ between medicines and from person to person.

You need to consider the side effects as well as the potential benefits when deciding to take a medicine for insomnia. No medicine should be taken for longer than the recommended period.

Melatonin only helps some people

In clinical trials, between 30% and 50% of people who took prolonged-release melatonin felt their sleep had improved. But so did 20% to 30% of people who took a dummy pill (placebo).

The time taken to fall asleep, quality of sleep and morning alertness may improve, but not the total length of time spent sleeping.

Many prescription sleep medicines are addictive

The prescription sleep medicines listed in Other medicines available for insomnia — like nitrazepam and zolpidem — are generally effective. But they can disturb the normal rhythm of sleep so it may not be as deep or restful.

They should only be used for a short time. If you take them for longer than 4 weeks, it can be difficult to stop. And when you do stop, you may get withdrawal symptoms — including muscle pain, tremors, anxiety and depression — or your insomnia might be worse than it was before (rebound insomnia).

For more information about zolpidem, see our NPS fact sheet.

There is currently no evidence to suggest that prolonged-release melatonin causes dependence or withdrawal effects.

Some sleep medicines may affect you during the day

Prolonged-release melatonin does not seem to cause problems with drowsiness or concentration during the day for most people.

But other sleep medicines can. Problems include drowsiness, poor concentration, memory loss and dizziness. These can increase the risk of a fall or a car accident.

Possible side effects when you’re asleep

Zolpidem and zopiclone (see Other medicines available for insomnia) have been linked to uncommon — but potentially dangerous — side effects like sleepwalking, sleep-eating and sleep-driving.

There is currently no evidence to suggest that other prescription sleep medicines or prolonged-release melatonin cause similar effects.

What about complementary medicines?

Some studies suggest that valerian can reduce the time it takes to fall asleep and improve the quality of sleep. But the studies only lasted for about 6 weeks, so they did not provide information about longer term use.

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What does prolonged-release melatonin cost?

Prolonged-release melatonin is not covered by the Pharmaceutical Benefits Scheme (PBS). It is only available by private prescription.

The price may vary between different pharmacies, but as an indication you should expect to pay around $30.00 for 3 weeks’ supply of prolonged-release melatonin tablets.

Other ways to relieve insomnia

Developing good sleep habits is more effective than using medicines. In the long term, most sleep medicines usually make sleep problems worse, not better.

If you’re having problems sleeping, these tips will get you on the right track:

  • Try to go to sleep and wake up at the same time each day.
  • Be as active as possible during the day and spend some time outdoors.
  • Reduce the amount of caffeine you have each day and avoid caffeinated drinks after lunchtime.
  • Avoid naps during the day. If you do nap, keep it to 20 minutes and before 3pm.
  • Avoid heavy meals, exercise or working on the computer late in the evening.
  • Avoid smoking and drinking alcohol in the evening.
  • Relax for 30 minutes before going to bed (e.g. take a warm bath or listen to music).
  • Don’t eat, work, watch television, read or discuss problems in bed.
  • Make sure your bedroom is not too hot or cold.
  • Ensure you are comfortable and your bedroom is quiet and dark.
  • Don’t stay in bed if you are awake for more than 20 minutes — go to another room and do something relaxing.

The following NPS resources with advice on how to get a good night’s sleep are available:

Where to find more information

You can find more information in the consumer medicine information (CMI). This will tell you:

  • who should not use the medicine
  • which other medicines should be avoided
  • how to take the medicine
  • most of the possible side effects
  • the ingredients.

You can get the CMI leaflet for Circadin from:

Information over the phone

NPS works with healthdirect Australia to provide the Medicines Line phone service for consumers.

To get more information about any medicine call 1300 MEDICINE (1300 633 424). This service is available from anywhere in Australia, Monday to Friday, 9am to 5pm AEST excluding NSW public holidays.

To report a side effect

Call the NPS Adverse Medicine Events (AME) Line on 1300 134 237, Monday to Friday, 9am to 5pm AEST excluding public holidays.

The AME Line is a service where you can report possible side effects of your medicine and contribute to national medicine safety efforts. Information on medicine-related side effects is passed on to the Therapeutic Goods Administration (TGA) for assessment, but your personal details will remain confidential and your privacy maintained.

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