What is melatonin?

Melatonin is a hormone (a chemical messenger) that is naturally made by a small gland (called the pineal gland) located in the centre of your brain which helps regulate your sleep patterns.  Although melatonin is made in the brain, it circulates through the bloodstream to all the areas of your body.

There is a natural daily rhythm to the production and release of melatonin. Our bodies naturally increase melatonin production in the evening with peak levels occurring at night (during darkness), while during the day (when there is light) the natural production of melatonin is reduced – which is why melatonin is sometimes called ‘the darkness hormone’.1 This natural cycle in the levels of circulating melatonin helps promote healthy sleep and orient our daily circadian rhythms.

Melatonin is also sometimes referred to as ‘the sleep hormone’. Although it is not actually essential for sleep we do sleep better when we are in phase with the highs and lows of our circulating melatonin and the rest of our circadian system.2 When you take Circadin, melatonin is gradually released during the night supplementing the low natural melatonin levels you may have and increasing your natural tendency to sleep well.2,3

Circadin is a prolonged release tablet

Not all melatonin tablets are the same. Circadin is a prolonged release tablet where the melatonin is released gradually over 8-10 hours4 – this slow release means melatonin levels slowly build up over the course of the night, reproducing the body’s natural night-time peak.5

In clinical trials, a single dose of 2 mg prolonged release melatonin (Circadin) has been shown to reproduce the normal night-time levels of melatonin.3,6,7 There is no evidence that taking more than the recommended dose of Circadin increases its sleep-inducing effects8 – taking more than one Circadin tablet will not help you get to sleep any quicker or make you sleep longer.5

Circadin is a pharmaceutical grade melatonin product and has been approved for use in Australia which means it has been carefully assessed for quality, efficacy and consistency.

Buying other melatonin products online from overseas can be tempting but it is not easy to tell which products are regulated – which means you don’t know who’s made them, doses can vary from batch to batch or they may contain contaminants. You may not be able to guarantee the strength or purity of the product you are buying.

Melatonin in sleep

Melatonin works together with your body’s circadian rhythm helping your body prepare for sleep – as it gets dark outside the pineal gland in your brain responds by producing more melatonin, signalling to your body that it’s time to sleep. When it starts to get light, the pineal gland starts to reduce the amount of melatonin it’s producing, which signals to the body it’s time to wake up.

Melatonin also plays a part in other functions in the body including helping to control our core body temperature (the temperature of the main part of our body that contains all our important internal organs such as the liver). As melatonin levels start to rise in the evening, our core temperature starts to cool slightly. This change in temperature is another important sleep signal for our bodies and can also influence how well we sleep, as we tend to sleep better when we’re cooler.  Our core temperature usually stays low during the night and then starts to rise in the morning before we wake up.

Melatonin in your body

The production of melatonin by the pineal gland and its circulation around the body occurs with a repeating daily (circadian) rhythm or cycle, with naturally low levels of melatonin during the day which then steadily increase to a peak at night (around 2 to 4 am).  Natural night-time levels of melatonin in your body are usually at least 10-fold higher than daytime concentrations.1

The prolonged release profile of Circadin is specifically designed to mimic the pineal gland’s natural melatonin secretion to help improve sleep quality and morning alertness.5,9

Studies have shown that the peak levels of Circadin melatonin are reached approximately 3 hours after you take the tablet and then remain high for about 3.5 hours, before gradually declining to low levels after about 10 hours.3,5

When you take Circadin you will usually feel a natural sleepiness and desire to go to bed between 1-2 hours after taking the recommended 2mg dose3 – as the melatonin is gradually released and reaches the right level for sleepiness. Melatonin levels peak and then follow the normal natural decline towards morning5 – allowing you to sleep and wake refreshed.4,10

If you have taken more traditional ‘sleeping pills’ in the past, you may notice that Circadin works a little differently – the effects are gradual. Circadin works with your body to help supplement low levels of night-time melatonin and gently lets your body know that it’s time to sleep so you can relax and fall asleep more easily and wake up refreshed the next morning.1

Circadin is usually well-tolerated by most people*1 – unlike many other types of sleeping pills that can leave you with daytime sleepiness, memory loss and poor concentration. Traditional types of sleeping pills can also have dependency and withdrawal issues, and leave you feeling ‘groggy’ or less alert after using them, increasing the likelihood of having a fall or an accident.

There is no evidence that taking more than the recommended dose of Circadin will increase its sleep promoting effects8 – the levels of night-time melatonin normally required by the body for sleep are provided by the recommended Circadin 2mg prolonged release melatonin dose.5,11

You can ask your doctor or pharmacist if you have any further questions about melatonin and its side-effects.

*Studies have been conducted in people aged 55 or over.


The information provided is not intended to be a substitute for professional medical advice. Please speak to a healthcare professional if you have any questions about your sleep problem or its treatment.

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  1. Masters A, et al. Brain Disord Ther. 2014;4(1):1000151.
  2. Arendt J. Front Endocrinol (Lausanne). 2019;10:391.
  3. CIRCADIN® Product Information. Last amended 11 November 2020.
  4. Wade AG, et al. Curr Med Res Opin. 2007;23(10):2597-2605. Funded by Neurim Pharmaceuticals, Tel Aviv, Israel.
  5. Zisapel N. Open Neuroendocrinology J. 2010;3:85-95.
  6. Zhdanova IV, Lynch HJ, Wurtman RJ. Sleep. 1997;20(10):899-907.
  7. Zisapel N. Drug Dev Res. 2000;50:226-234. Funded by Neurim Pharmaceuticals, Tel Aviv, Israel.
  8. CIRCADIN® Consumer Medicine Information (CMI).
  9. Zisapel N. British Journ. of Pharmacology (2018) 175 3190–3199. Sponsored by Neurim Pharmaceuticals, Tel Aviv, Israel.
  10. Schutte-Rodin S, et al. J Clin Sleep Med. 2008;4(5):487-504.
  11. Mishima K, et al. J Clin Endocrinol Metab. 2001;86(1):129-34.