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Circadin Prolonged Release Tablets

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Generic Name: Melatonin
Product Name: Circadin Prolonged Release Tablets


Circadin is used to treat individuals aged ≥ 55 years who experience primary insomnia. This condition is characterised by poor quality sleep. Circadin is used to improve sleep quality and morning alertness.

For more information about sleep, including how much is good for you, tips for getting more sleep, and sleep disorders, as well as some useful videos, see



Melatonin is a hormone produced naturally by the human body. However, the amount of melatonin an individual’s body produces decreases with age.

Melatonin is secreted by the pineal gland (a hormone-producing gland in the brain) according to a circadian rhythm – that is, a time pattern that is repeated each day. The pineal gland begins secreting melatonin each day in the evening. Secretion peaks in the early hours of the morning (2–4 am), then diminishes in the remainder of the night and remains low throughout the day, before melatonin secretion commences again the following evening.

Melatonin, both naturally produced and added to the body in medication, functions to control the body’s circadian rhythm (its rhythm over a 24 hour period, including patterns of sleep and wakefulness). It also controls the body’s response to the dark-light cycle. It induces a hypnotic effect and increases sleepiness.

In ageing individuals (≥ 55 years old) who have naturally reduced levels of melatonin, administration of melatonin-containing tablets should improve sleep quality by improving circadian rhythm regulation.

Dose advice

Dose information

Individuals using Circadin should take one tablet, which contains 2 mg of the active ingredient melatonin, each day. The tablet should be swallowed whole and taken after food, 1–2 hours before it is time to sleep. Circadin should be taken for as long as your doctor prescribes it.

If you have any queries about the correct way to use Circadin, please ask your doctor.


Circadin should not be used under certain conditions. Tell your doctor if you have:

  • Allergies: So that the doctor can check whether or not you are not allergic to any of the ingredients in the medicine.


Special care needs to be taken when using Circadin under certain conditions. Tell your doctor if you have:

  • Safety risks which may be worsened by drowsiness: Circadin causes drowsiness. As a precautionary measure, individuals taking Circadin should not drive or operate machinery.
  • An autoimmune disease: Circadin is not recommended for use by individuals with autoimmune diseases as studies have not yet established whether or not Circadin is safe for these individuals to use.
  • Galatose intolerance, LAPP lactase deficiency, glucose-galactose malabsorption: Circadin contains lactose and is not recommended for use by individuals with these conditions;
  • Kidney disorders;
  • Liver disorders;
  • Are taking any other medications: Some medications alter the effects of Circadin. Your doctor may need to adjust the dose of Circadin or other medications which you are also taking, if the medications are taken at the same time.

Use in pregnancy

Circadin is a Pregnancy Category B3 medication. It is not recommended for use by pregnant women, as studies have not been undertaken to determine whether or not it is safe for pregnant women to use the medicine.


Circadin is not recommended for use by breastfeeding women and its use is not indicated in women of reproductive age. The active ingredient melatonin is likely to be transferred to breastfed babies in human breast milk. No human studies have been undertaken to determine the effect of such melatonin transfer on infant development. Animal studies indicate that high doses of melatonin impair the development of infant rats.

Use in children

Studies have not yet been undertaken to determine whether or not it is safe for individuals < 18 years of age to use Circadin. The drug is therefore not recommended for use in children and adolescents.


Circadin is Schedule S4.1

Common side effects

All medicines have side effects. Most commonly the side effects are minor; however, some can be more serious. Usually the benefits of taking a medication outweigh the associated side effects. Your doctor would have considered these side effects before starting you on Circadin.

Common side effects

Common side effects are those that occur in 1–10% of people given Circadin. These include:

Uncommon side effects

Side effects that occur in 0.1–1%  of people given Circadin are considered uncommon. People do not necessarily experience any of these side effects, so do not become alarmed by this list:

Rare side effects

Rare side effects are those that occur in 0.01–0.1% of people given Circadin. These include:

If you experience any of the listed side effects, or any other symptoms that appear abnormal or unusual, please tell your doctor.

Useful Resources:

Sleep Diary 

Download the Sleep Diary.


  1. Product Information: Circadin Prolonged Release Tablets. Croydon, VIC: Sigma Pharmaceuticals (Australia) Pty Ltd; 4 January 2011.

Related documents:


For further information talk to your doctor.

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Posted On: 3 May, 2010
Modified On: 14 January, 2011
Reviewed On: 12 January, 2011

Created by: myVMC