Sounds like 'mel-a-to-nin'

Melatonin is used to treat sleep problems. Find out how to take it safely and possible side effects.

Type of medicine Also called
  • Medicine to improve sleep (hypnotic)
  • Circadin®
  • Melatonin (Twinlab)®
  • Country Life®
  • Melatonin (Generic Partners)

What is melatonin?

Melatonin is a hormone produced by a gland in your body known as the pineal gland. It helps to control your body's sleep pattern and sleep–wake cycle. The level of melatonin in your body increases soon after the onset of darkness and is highest between 2–3 am. Melatonin production is suppressed by light. It seems that less melatonin is produced as you age. In New Zealand melatonin is available as tablets and capsules and has different uses.

Sleep problems
A slow release tablet (it releases melatonin slowly over a few hours) is available on prescription. It can be prescribed to help with sleep problems in people over 55 years. Melatonin can also be purchased for this use following a discussion with a pharmacist who has completed melatonin certification. It is best to use melatonin for a short time only to help you get back into a good sleep habit. Read more about sleep problems (insomnia) and tips to improve your sleeping habits.

Neurodevelopment disorders in children
Melatonin may be prescribed for children and young people up to the age of 18 years who have neurodevelopment disorders that make it difficult to sleep.

Melatonin (immediate release) may help prevent or reduce jet lag, particularly if you are flying across 5 or more time zones in an easterly direction, but it is not approved for this use in New Zealand.

Note: The immediate-release melatonin is not funded in New Zealand and the slow-release melatonin may not be as useful for jet lag. The timing of the dose is critical; if taken at the wrong time, adaptation to local time will be delayed. Melatonin is most effective when taken as 0.5–5 mg in the evening after arrival at the destination. Taking melatonin before travel is not recommended. 

How to take melatonin

  • Timing: For sleep problems, take your melatonin dose 1 or 2 hours before bedtime, after a meal or with a snack. It is important to take your dose at the correct time. If taken at the wrong time of the day it is likely to cause daytime sleepiness, particularly if combined with other medicines.
  • Swallow slow-release tablets whole: Do not crush, chew or divide them because this will release all the medication at once. The slow-release tablets have been designed to release the right dose of medicine while you sleep. If you crush, chew or divide the tablet they will not work properly. 
  • Effects of melatonin may not be immediate: The effects of melatonin may not be immediate and it may take a few days for you to experience the full benefits. It's important to take your dose once
    daily at night rather than every now and again (intermittently).
  • Missed dose: It is not harmful if you miss your melatonin dose. If you forget to take your dose at the usual time, but you remember before you go to sleep, take it when you remember. But if you do not remember until the following day, just take the next dose at the right time. Do not take double the dose.
  • Do not take melatonin for longer than your doctor advises: Melatonin may be prescribed for up to 13 weeks. It does not work in everyone, so see your doctor if you keep having problems with your sleep.

Cautions while taking melatonin

  • Alcohol: Limit or avoid alcohol while taking melatonin because alcohol can affect how it works.
  • Effects on driving: Although melatonin appears to have little effect on the ability to drive, it is best to avoid driving for the rest of the evening after taking melatonin.
  • Interaction with other medicines: Melatonin can interact with other medicines, so check with your doctor or pharmacist before starting melatonin or before starting any new medicines. This is especially important if you are taking other medicines that can cause drowsiness or if you are taking warfarin (as it may alter the INR).
  • Do not share this medicine with others

Precautions – before taking melatonin

  • Do you have an autoimmune disease (a condition in which your body is attacked by its own overactive immune system) such as rheumatoid arthritis, multiple sclerosis or lupus?
  • Do you have problems with the way your kidney or liver works?
  • Do you have epilepsy, high blood pressure or diabetes?
  • Do you have depression?
  • Are you pregnant or planning a pregnancy?
  • Are you breastfeeding?

If so, it’s important that you tell your doctor before you start melatonin. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care.

Possible side effects

Like all medicines, melatonin can cause side effects, although not everyone gets them. Often side effects improve as your body adjusts to the new medicine.

Side effects What should I do?
  • Feeling tired or sleepy
  • Drowsiness
  • Be careful when driving or using tools until you know how this medicine affects you.
  • Indigestion
  • Stomach upset
  • Nausea (feeling sick)
  • Try taking melatonin with food or a snack.
  • Muscle, bone or joint pains 

  • Tell your doctor if troublesome.

Learn more

The following links have more information about melatonin. Be aware that websites from other countries may have information that differs from New Zealand recommendations.

Circadin  Medsafe, NZ
Melatonin Sleep Health Foundation, Australia


  1. Melatonin New Zealand Formulary
  2. Melatonin New Zealand Formulary for children
  3. Melatonin – is it worth losing any sleep over? BPAC, NZ, 2015
  4. Melatonin – don't lose sleep over it SafeRx, NZ, 2019
Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 09 Nov 2019